scholarly journals Switching of filamin polypeptides during myogenesis in vitro.

1983 ◽  
Vol 96 (2) ◽  
pp. 321-329 ◽  
Author(s):  
R H Gomer ◽  
E Lazarides
Keyword(s):  
Molecular Weight ◽  
Peptide Mapping ◽  
Short Pulse ◽  
Actin Binding ◽  
Gene Products ◽  
Skeletal Myogenesis ◽  
New Class ◽  
Filament Bundles ◽  
Peptide Maps

During chicken skeletal myogenesis in vitro, the actin-binding protein filamin is present at first in association with actin filament bundles both in myoblasts and in myotubes early after fusion. Later in mature myotubes it is found in association with myofibril Z disks. These two associations of filamin are separated by a period of several days, during which the protein is absent from the cytoplasm of differentiating myotubes (Gomer, R., and E. Lazarides, 1981, Cell, 23:524-532). To characterize the two classes of filamin polypeptides we have compared, by two-dimensional peptide mapping, 125I-labeled filamin immunoprecipitated from myoblasts and fibroblasts to filamin immunoprecipitated from mature myotubes and adult skeletal myofibrils. Myoblast filamin is highly homologous to fibroblast and purified chicken gizzard filamins. Mature myotube and adult myofibril filamins are highly homologous but exhibit extensive peptide differences with respect to the other three classes of filamin. Comparison of peptide maps from immunoprecipitated 35S-methionine-labeled filamins also shows that fibroblast and myoblast filamins are highly homologous but show substantial peptide differences with respect to mature myotube filamin. Filamins from both mature myotubes and skeletal myofibrils exhibit a slightly higher electrophoretic mobility than gizzard, fibroblast, and myoblast filamins. Short pulse-labeling studies show that mature myotube filamin is synthesized as a lower molecular weight variant and is not derived from a higher molecular weight precursor. These results suggest that myoblast and mature myotube filamins are distinct gene products and that during skeletal myogenesis in vitro one class of filamin polypeptides is replaced by a new class of filamin polypeptides, and that the latter is maintained into adulthood.

Conjugates of Classical DNA/RNA Binder with Nucleobase: Chemical, Biochemical and Biomedical Applications

2019 ◽  
Vol 26 (30) ◽  
pp. 5609-5624
Author(s):  
Dijana Saftić ◽  
Željka Ban ◽  
Josipa Matić ◽  
Lidija-Marija Tumirv ◽  
Ivo Piantanida
Keyword(s):  
Molecular Weight ◽  
Small Molecules ◽  
Biomedical Applications ◽  
Protein Targets ◽  
New Class ◽  
Rna Targets ◽  
Covalently Linked ◽  
Structural Aspects

: Among the most intensively studied classes of small molecules (molecular weight < 650) in biomedical research are small molecules that non-covalently bind to DNA/RNA, and another intensively studied class is nucleobase derivatives. Both classes have been intensively elaborated in many books and reviews. However, conjugates consisting of DNA/RNA binder covalently linked to nucleobase are much less studied and have not been reviewed in the last two decades. Therefore, this review summarized reports on the design of classical DNA/RNA binder – nucleobase conjugates, as well as data about their interactions with various DNA or RNA targets, and even in some cases protein targets are involved. According to these data, the most important structural aspects of selective or even specific recognition between small molecule and target are proposed, and where possible related biochemical and biomedical aspects were discussed. The general conclusion is that this, rather new class of molecules showed an amazing set of recognition tools for numerous DNA or RNA targets in the last two decades, as well as few intriguing in vitro and in vivo selectivities. Several lead research lines show promising advancements toward either novel, highly selective markers or bioactive, potentially druggable molecules.

Phosphorylated and unphosphorylated forms of cardiac tropomyosin

1982 ◽  
Vol 60 (12) ◽  
pp. 1116-1122 ◽  
Author(s):  
Magdalena Segura ◽  
Elizabeth Palmer ◽  
José L. Saborío
Keyword(s):  
Molecular Weight ◽  
Posttranslational Modifications ◽  
Chick Embryos ◽  
Isoelectric Points ◽  
Reticulocyte Lysate ◽  
Peptide Maps ◽  
Translational Product

Cardiac tropomyosin from 20-day-old chick embryos is composed of three different polypeptides with the same molecular weight but different isoelectric points. These polypeptides, which are designated as α1, α2, and α3, have identical peptide maps. In vitro, however, only polypeptide α1 is synthesized in a reticulocyte lysate programmed with cardiac RNA. These results, together with the observations indicating that tropomyosin α2 corresponds to a phosphorylated polypeptide, suggest that only tropomyosin α1 corresponds to a primary translational product and that forms α2 and α3 are derived from α1 as a consequence of posttranslational modifications.

scholarly journals Isolation and characterization of a regulated form of actin depolymerizing factor

1993 ◽  
Vol 122 (3) ◽  
pp. 623-633 ◽  
Author(s):  
TE Morgan ◽  
RO Lockerbie ◽  
LS Minamide ◽  
MD Browning ◽  
JR Bamburg
Keyword(s):  
Muscle Development ◽  
Peptide Mapping ◽  
Actin Binding ◽  
Actin Assembly ◽  
Actin Depolymerizing Factor ◽  
Isolation And Characterization ◽  
Relative Molecular Weight

Actin depolymerizing factor (ADF) is an 18.5-kD protein with pH-dependent reciprocal F-actin binding and severing/depolymerizing activities. We previously showed developing muscle down-regulates ADF (J. R. Bamburg and D. Bray. 1987. J. Cell Biol. 105: 2817-2825). To further study this process, we examined ADF expression in chick myocytes cultured in vitro. Surprisingly, ADF immunoreactivity increases during the first 7-10 d in culture. This increase is due to the presence of a new ADF species with higher relative molecular weight which reacts identically to brain ADF with antisera raised against either brain ADF or recombinant ADF. We have purified both ADF isoforms from myocytes and have shown by peptide mapping and partial sequence analysis that the new isoform is structurally related to ADF. Immunoprecipitation of both isoforms from extracts of cells prelabeled with [32P]orthophosphate showed that the new isoform is radiolabeled, predominantly on a serine residue, and hence is called pADF. pADF can be converted into a form which comigrates with ADF on 1-D and 2-D gels by treatment with alkaline phosphatase. pADF has been quantified in a number of cells and tissues where it is present from approximately 18% to 150% of the amount of unphosphorylated ADF. pADF, unlike ADF, does not bind to G-actin, or affect the rate or extent of actin assembly. Four ubiquitous protein kinases failed to phosphorylate ADF in vitro suggesting that ADF phosphorylation in vivo is catalyzed by a more specific kinase. We conclude that the ability to regulate ADF activity is important to muscle development since myocytes have both pre- and posttranslational mechanisms for regulating ADF activity. The latter mechanism is apparently a general one for cell regulation of ADF activity.

scholarly journals Purification of the 300K intermediate filament-associated protein and its in vitro recombination with intermediate filaments.

1985 ◽  
Vol 101 (3) ◽  
pp. 802-813 ◽  
Author(s):  
N Lieska ◽  
H Y Yang ◽  
R D Goldman
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Intermediate Filament ◽  
Peptide Mapping ◽  
Amorphous Material ◽  
Gel Filtration ◽  
Weight Fraction ◽  
High Molecular Weight Fraction ◽  
In Vitro Recombination

IFAP-300K is a 300,000-mol-wt intermediate filament-associated protein previously identified in the baby hamster kidney fibroblastic cell line (BHK-21) by a monoclonal antibody (Yang H.-Y., N. Lieska, A. E. Goldman, and R. D. Goldman, 1985, J. Cell Biol., 100: 620-631). In the present study, this molecule was purified from the high salt/detergent-insoluble cytoskeletal preparation of these cells. Gel filtration on Sephacryl S-400 in the presence of 7.2 M urea allowed separation of the high molecular weight fraction from the structural intermediate filament (IF) subunits desmin and vimentin, designated 54K and 55K, respectively, and other low molecular weight polypeptides. DE-52 cellulose chromatography of the high molecular weight fraction using a linear NaCl gradient in 8 M urea yielded a pure 300,000-mol-wt species which was confirmed to be IFAP-300K by immunological and peptide mapping criteria. Two-dimensional PAGE of native BHK IF preparations followed by immunoblot analysis demonstrated the inability of the IFAP-300K-immunoreactive material to enter the first dimensional gel except as a 200,000-mol-wt doublet which presumably represented a major proteolytic derivative of IFAP-300K. The molecule's pl of 5.35, as determined by chromatofocusing, and its amino acid composition were extremely similar to those of BHK cell vimentin/desmin despite their non-identity. Ultrastructurally, IFAP-300K preparations in low salt buffers existed as particles composed of one or two elliptical units measuring 16 X 20 nm. In physiological salt buffers, the predominant entities were large, elongated aggregates of the elliptical units, which were able to be decorated by using the immunogold technique with monoclonal anti-IFAP-300K. Compared with the morphology of homopolymer vimentin IF, in vitro recombination studies using column-purified vimentin and IFAP-300K demonstrated the additional presence of aggregates similar in appearance to IFAP-300K at points of contact between IFs. Antibody decoration and immunogold labeling of these recombined preparations using rabbit antidesmin/vimentin and monoclonal anti-IFAP-300K confirmed the identity of the inter-filament, amorphous material as IFAP-300K. The presence of IFAP-300K at many points of intersection and lateral contact between IFs, as well as at apparent inter-filament "bridges," in these recombined specimens was identical to that seen both in situ and in native IF preparations. No such co-sedimentation was found in vitro between actin and IFAP-300K. No effects of IFAP-300K upon the kinetics of IF polymerization were detected by turbidimetric measurements.

Mutations affecting assembly and stability of tubulin: evidence for a nonessential beta-tubulin in CHO cells

1987 ◽  
Vol 7 (8) ◽  
pp. 2700-2707
Author(s):  
B Boggs ◽  
F Cabral
Keyword(s):  
Molecular Weight ◽  
Gene Product ◽  
Cho Cells ◽  
Peptide Mapping ◽  
Chinese Hamster ◽  
Apparent Molecular Weight ◽  
Tubulin Gene ◽  
Beta Tubulin ◽  
Beta Tubulin Gene

Eight strains of Chinese hamster ovary (CHO) cells having an assembly-defective beta-tubulin were found among revertants of strain Cmd 4, a mutant with a conditional lethal mutation in a beta-tubulin gene (F. Cabral, M. E. Sobel, and M. M. Gottesman, Cell 20:29-36, 1980). The altered beta-tubulins in these strains have electrophoretically silent alterations or, in some cases, an increase or a decrease in apparent molecular weight based on their migration in two-dimensional gels. The identity of these variant proteins as beta-tubulin was confirmed by peptide mapping, which also revealed the loss of distinct methionine-containing peptides in the assembly-defective beta-tubulins of lower apparent molecular weight. The altered mobility of these beta-tubulin polypeptides was not the result of a posttranslational modification, since the altered species could be labeled in very short incubations with [35S]methionine and were found among in vitro-translated polypeptides by using purified mRNA. In at least one strain, an altered DNA restriction fragment could be demonstrated, suggesting that an alteration occurred in one of the structural genes for beta-tubulin. Assembly-defective beta-tubulin was unstable and turned over with a half-life of only 1 to 2 h in exponentially growing cells. This rapid degradation of a tubulin gene product resulted in approximately 30% lower steady-state levels of both alpha- and beta-tubulin yet did not affect the growth rate of the cells or the distribution of the microtubules as judged by immunofluorescence microscopy. These results argue that CHO cells possess a beta-tubulin gene product that is not essential for survival.

Identification of gene products from cloned fragments of the left arm of λdapB2

1982 ◽  
Vol 60 (3) ◽  
pp. 338-346 ◽  
Author(s):  
George A. Mackie ◽  
Gay D. Parsons
Keyword(s):  
Molecular Weight ◽  
Trna Synthetase ◽  
Synthetase Activity ◽  
Gene Products ◽  
Positive Identification ◽  
30S Subunit ◽  
Bacterial Genes ◽  
The Right ◽  
Coding Potential

A set of recombinant plasmids encompassing the bacterial substitution in λdapB2 (Mackie, G. A. (1980) J. Biol. Chem. 255, 8928–8935) has been characterized genetically by complementation and biochemically by an analysis of the proteins encoded by individual plasmids in vitro. In addition to a cluster of four genes which includes the dapB locus, a total of seven gene products has been identified. One of these is ribosomal protein S20, whose gene (rpsT) has been localized to a 0.56-kilobase segment of DNA bounded by HindIII and HindII sites. Positive identification of this gene on plasmids pGM9 and pGP2 has been achieved by analysis of the products encoded by these plasmids in vitro and by the ability of pGM9 to complement a strain lacking S20 among its 30S subunit proteins. A second gene is that for isoleucyl tRNA synthetase (ileS). Its presence on pGM21 has been ascertained by the latter's ability to direct the synthesis of a protein in vitro with the size anticipated for this gene product. Extracts of cells harbouring this plasmid also exhibit greater isoleucyl tRNA synthetase activity than parental extracts. A third gene is at least 1.3 kilobases distant from rpsT and encodes a protein of 24 000 molecular weight, of unknown function. This locus is in turn about 6.5 kilobases from λ gene E. The latter gene, and several others, all of which likely derive from λ DNA are carried on a 5.2-kilobase fragment inserted in the piasmid pGM11 which includes the junction between phage and bacterial sequences on the left side of λdapB2. This fragment of DNA is inserted into the vector in a manner which permits the coupled transcription and translation of λ genes D and E in vitro, despite the absence of their natural promoter. The most striking feature of the organization of the bacterial genes on λdapB2 is the clustering of genes for polypeptides in the right half of the bacterial substitution in contrast to the apparent minimal use of the coding potential in the left half of the substitution.

scholarly journals Utrophin Binds Laterally along Actin Filaments and Can Couple Costameric Actin with Sarcolemma When Overexpressed in Dystrophin-deficient Muscle

2002 ◽  
Vol 13 (5) ◽  
pp. 1512-1521 ◽  
Author(s):  
Inna N. Rybakova ◽  
Jitandrakumar R. Patel ◽  
Kay E. Davies ◽  
Peter D. Yurchenco ◽  
James M. Ervasti
Keyword(s):  
Molecular Weight ◽  
Actin Filaments ◽  
Binding Proteins ◽  
Full Length ◽  
Actin Binding ◽  
Lateral Association ◽  
Cortical Cytoskeleton ◽  
Molecular Dimensions ◽  
Native Molecular Weight

Dystrophin is widely thought to mechanically link the cortical cytoskeleton with the muscle sarcolemma. Although the dystrophin homolog utrophin can functionally compensate for dystrophin in mice, recent studies question whether utrophin can bind laterally along actin filaments and anchor filaments to the sarcolemma. Herein, we have expressed full-length recombinant utrophin and show that the purified protein is fully soluble with a native molecular weight and molecular dimensions indicative of monomers. We demonstrate that like dystrophin, utrophin can form an extensive lateral association with actin filaments and protect actin filaments from depolymerization in vitro. However, utrophin binds laterally along actin filaments through contribution of acidic spectrin-like repeats rather than the cluster of basic repeats used by dystrophin. We also show that the defective linkage between costameric actin filaments and the sarcolemma in dystrophin-deficientmdx muscle is rescued by overexpression of utrophin. Our results demonstrate that utrophin and dystrophin are functionally interchangeable actin binding proteins, but that the molecular epitopes important for filament binding differ between the two proteins. More generally, our results raise the possibility that spectrin-like repeats may enable some members of the plakin family of cytolinkers to laterally bind and stabilize actin filaments.

scholarly journals Structural analysis of the variable major proteins of Borrelia hermsii.

1983 ◽  
Vol 158 (6) ◽  
pp. 2127-2140 ◽  
Author(s):  
A G Barbour ◽  
O Barrera ◽  
R C Judd
Keyword(s):  
Molecular Weight ◽  
Antigenic Variation ◽  
Amino Acid Sequences ◽  
Silver Stain ◽  
Borrelia Hermsii ◽  
Pii Proteins ◽  
Variable Major Proteins ◽  
Peptide Maps

Borrelia hermsii undergoes spontaneous antigenic variation in vivo and in vitro. Serotype specificity is associated with expression of one of a family of molecular weight-variable proteins, the pI proteins. We studied the structure of the pI proteins as well as the molecular weight-invariable pII proteins of three serotypes of B. hermsii HS1: C, 7, and 21. The techniques used were one-dimensional (1-D) mapping of Staphylococcus aureus V8 protease-generated peptides and two-dimensional (2-D) mapping of alpha-chymotrypsin-generated peptides. The pI and pII proteins were isolated by excision of polypeptides from stained polyacrylamide gel electropherograms. The 1-D peptide patterns were visualized by fluorography of intrinsically [14C]leucine-labeled proteins or by silver stain. Before 2-D mapping, polypeptides in excised gel fragments were labeled with 125I in the presence of chloramine-T. We also compared the 2-D peptide maps of pI proteins, pI7 and pI21, after their surface-exposed portions were radioiodinated using 1,3,4,6-tetrachloro-3 alpha,6 alpha-diphenylglycoluril (Iodogen). The I-D and 2-D peptide maps demonstrated the following: (a) pI proteins of the three serotypes have few V8 protease- or chymotrypsin-generated peptides in common, and (b) pI proteins of each serotype appear to be identical. The findings suggest that pI protein variability derives from extensive differences in the amino acid sequences of these proteins.

scholarly journals Mutations affecting assembly and stability of tubulin: evidence for a nonessential beta-tubulin in CHO cells.

1987 ◽  
Vol 7 (8) ◽  
pp. 2700-2707 ◽  
Author(s):  
B Boggs ◽  
F Cabral
Keyword(s):  
Molecular Weight ◽  
Gene Product ◽  
Cho Cells ◽  
Peptide Mapping ◽  
Chinese Hamster ◽  
Apparent Molecular Weight ◽  
Tubulin Gene ◽  
Beta Tubulin ◽  
Beta Tubulin Gene

Eight strains of Chinese hamster ovary (CHO) cells having an assembly-defective beta-tubulin were found among revertants of strain Cmd 4, a mutant with a conditional lethal mutation in a beta-tubulin gene (F. Cabral, M. E. Sobel, and M. M. Gottesman, Cell 20:29-36, 1980). The altered beta-tubulins in these strains have electrophoretically silent alterations or, in some cases, an increase or a decrease in apparent molecular weight based on their migration in two-dimensional gels. The identity of these variant proteins as beta-tubulin was confirmed by peptide mapping, which also revealed the loss of distinct methionine-containing peptides in the assembly-defective beta-tubulins of lower apparent molecular weight. The altered mobility of these beta-tubulin polypeptides was not the result of a posttranslational modification, since the altered species could be labeled in very short incubations with [35S]methionine and were found among in vitro-translated polypeptides by using purified mRNA. In at least one strain, an altered DNA restriction fragment could be demonstrated, suggesting that an alteration occurred in one of the structural genes for beta-tubulin. Assembly-defective beta-tubulin was unstable and turned over with a half-life of only 1 to 2 h in exponentially growing cells. This rapid degradation of a tubulin gene product resulted in approximately 30% lower steady-state levels of both alpha- and beta-tubulin yet did not affect the growth rate of the cells or the distribution of the microtubules as judged by immunofluorescence microscopy. These results argue that CHO cells possess a beta-tubulin gene product that is not essential for survival.

scholarly journals Identification and localization of immunoreactive forms of caldesmon in smooth and nonmuscle cells: a comparison with the distributions of tropomyosin and alpha-actinin.

1985 ◽  
Vol 100 (5) ◽  
pp. 1656-1663 ◽  
Author(s):  
A Bretscher ◽  
W Lynch
Keyword(s):  
Molecular Weight ◽  
Smooth Muscle ◽  
Cultured Cells ◽  
Stress Fibers ◽  
Actin Binding ◽  
Cross Linking ◽  
Light Microscope Level ◽  
Chicken Gizzard ◽  
Heat Stable

Caldesmon is an F-actin cross-linking protein of chicken gizzard smooth muscle whose F-actin binding activity can be regulated in vitro by Ca2+-calmodulin (Sobue, K., Y. Muramoto, M. Fujita, and S. Kakiuchi, 1981, Proc. Natl. Acad. Sci. USA, 78:5652-5655). It is a rod-shaped, heat-stable, F-actin bundling protein and is the most abundant F-actin cross-linking protein of chicken gizzard smooth muscle presently known (Bretscher, A., 1984, J. Biol. Chem., 259:12873-12880). We report the use of polyclonal antibodies to caldesmon to investigate its distribution and localization in other cells. Using immune blotting procedures, we have detected immunoreactive, heat-stable forms of caldesmon in cultured cells having either approximately the same apparent polypeptide molecular weight as gizzard caldesmon (120,000-140,000) or a substantially lower molecular weight (71,000-77,000). Through use of affinity-purified antibodies in indirect immunofluorescence microscopy, we have localized the immunoreactive forms to the terminal web of the brush border of intestinal epithelial cells and to the stress fibers and ruffling membranes of cultured cells. At the light microscope level caldesmon is distributed in a periodic fashion along stress fibers that is coincident with the distribution of tropomyosin and complementary to the distribution of alpha-actinin.

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