scholarly journals A Motif in the Clathrin Heavy Chain Required for the Hsc70/Auxilin Uncoating Reaction

2008 ◽  
Vol 19 (1) ◽  
pp. 405-413 ◽  
Author(s):  
Iris Rapoport ◽  
Werner Boll ◽  
Anan Yu ◽  
Till Böcking ◽  
Tom Kirchhausen
Keyword(s):  
Heavy Chain ◽  
Sequence Motif ◽  
Heavy Chains ◽  
C Terminus ◽  
Hsp70 Chaperone ◽  
Reaction Proceeds ◽  
Hsc 70 ◽  
Heat Shock Cognate Protein ◽  
Cognate Protein

The 70-kDa heat-shock cognate protein (Hsc70) chaperone is an ATP-dependent “disassembly enzyme” for many subcellular structures, including clathrin-coated vesicles where it functions as an uncoating ATPase. Hsc70, and its cochaperone auxilin together catalyze coat disassembly. Like other members of the Hsp70 chaperone family, it is thought that ATP-bound Hsc70 recognizes the clathrin triskelion through an unfolded exposed hydrophobic segment. The best candidate is the unstructured C terminus (residues 1631–1675) of the heavy chain at the foot of the tripod below the hub, containing the sequence motif QLMLT, closely related to the sequence bound preferentially by the substrate groove of Hsc70 ( Fotin et al., 2004b ). To test this hypothesis, we generated in insect cells recombinant mammalian triskelions that in vitro form clathrin cages and clathrin/AP-2 coats exactly like those assembled from native clathrin. We show that coats assembled from recombinant clathrin are good substrates for ATP- and auxilin-dependent, Hsc70-catalyzed uncoating. Finally, we show that this uncoating reaction proceeds normally when the coats contain recombinant heavy chains truncated C-terminal to the QLMLT motif, but very inefficiently when the motif is absent. Thus, the QLMLT motif is required for Hsc-70–facilitated uncoating, consistent with the proposal that this sequence is a specific target of the chaperone.

Psychophysiological stress induces heat shock cognate protein (HSC)70 mRNA in the cerebral cortex and stomach of rats

1995 ◽  
Vol 675 (1-2) ◽  
pp. 98-102 ◽  
Author(s):  
Shin Fukudo ◽  
Koji Abe ◽  
Michio Hongo ◽  
Atsushi Utsumi ◽  
Yasuto Itoyama
Keyword(s):  
Cerebral Cortex ◽  
Heat Shock ◽  
Psychophysiological Stress ◽  
Hsc 70 ◽  
Heat Shock Cognate Protein ◽  
Cognate Protein

scholarly journals The substructure of isolated and in situ outer dynein arms of sea urchin sperm flagella.

1985 ◽  
Vol 101 (4) ◽  
pp. 1400-1412 ◽  
Author(s):  
W S Sale ◽  
U W Goodenough ◽  
J E Heuser
Keyword(s):  
Sea Urchin ◽  
Heavy Chain ◽  
Heavy Chains ◽  
Low Salt ◽  
Spherical Head ◽  
Dynein Arms ◽  
Sea Urchin Sperm ◽  
Globular Head

Outer-arm dynein from the sperm of the sea urchin S. purpuratus was adsorbed to mica flakes and visualized by the quick-freeze, deep-etch technique. Replicas reveal particles comprised of two globular heads joined by two irregularly shaped stems which make contact along their length. One head is pear-shaped (18.5 X 12.5 nm) and the other is spherical (14.5-nm diam). The stems are decorated by a complex of bead-like subunits. The same two-headed protein is found in the 21S dynein-1 fraction of sucrose gradients. The beta-heavy chain/intermediate chain 1 (beta/IC-1) dynein subfraction, produced by low-salt dialysis and zonal centrifugation of the high-salt-extracted dynein-1, contains only single-headed molecules with single stems. These heads are predominantly pear-shaped (18.5 X 12.5 nm). Since 21S dynein-1 contains two heavy chains (alpha and beta), and the beta/IC-1 subfraction is comprised of only the beta-heavy chain (Tang et al., 1982, J. Biol. Chem. 257: 508-515), we conclude that each head is formed by a heavy chain, that the pear-shaped head contains the beta-heavy chain, and that the spherical head contains the alpha-heavy chain. The in situ outer dynein arms of demembranated sperm were also studied by the quick-freeze, deep-etch method. When frozen in reactivation buffer devoid of ATP, each arm consists of a large globular head that attaches to the A-microtubule by distally skewed subunits and attaches to the B-microtubule by a slender stalk. In ATP, this head shifts its orientation such that it can be seen to be constructed from two globular domains. We offer possible correlates between the in situ and the in vitro images, and we compare the structure of sea-urchin dynein with dynein previously described from Chlamydomonas and Tetrahymena.

scholarly journals Translocation of peptides through microsomal membranes is a rapid process and promotes assembly of HLA-B27 heavy chain and beta 2-microglobulin translated in vitro.

1991 ◽  
Vol 115 (4) ◽  
pp. 959-970 ◽  
Author(s):  
F Lévy ◽  
R Larsson ◽  
S Kvist
Keyword(s):  
Mhc Class I ◽  
Heavy Chain ◽  
Peptide Binding ◽  
Class I ◽  
Hla B27 ◽  
Heavy Chains ◽  
Microsomal Membranes ◽  
Beta 2 ◽  
Beta 2 Microglobulin

We have translated major histocompatibility complex (MHC) class I heavy chains and human beta 2-microglobulin in vitro in the presence of microsomal membranes and a peptide from the nucleoprotein of influenza A. This peptide stimulates assembly of HLA-B27 heavy chain and beta 2-microglobulin about fivefold. By modifying this peptide to contain biotin at its amino terminus, we could precipitate HLA-B27 heavy chains with immobilized streptavidin, thereby directly demonstrating class I heavy chain-peptide association under close to physiological conditions. The biotin-modified peptide stimulates assembly to the same extent as the unmodified peptide. Both peptides bind to the same site on the HLA-B27 molecule. Immediately after synthesis of the HLA-B27 heavy chain has been completed, it assembles with beta 2-microglobulin and peptide. These interactions occur in the lumen of the microsomes (endoplasmic reticulum), demonstrating that the peptide must cross the microsomal membrane in order to promote assembly. The transfer of peptide across the microsomal membrane is a rapid process, as peptide binding to heavy chain-beta 2-microglobulin complexes is observed in less than 1 min after addition of peptide. By using microsomes deficient of beta 2-microglobulin (from Daudi cells), we find a strict requirement of beta 2-microglobulin for detection of peptide interaction with the MHC class I heavy chain. Furthermore, we show that heavy chain interaction with beta 2-microglobulin is likely to precede peptide binding. Biotin-modified peptides are likely to become a valuable tool in studying MHC antigen interaction and assembly.

scholarly journals Nodular Glomerulosclerosis with Deposition of Monoclonal Immunoglobulin Heavy Chains Lacking CH1

1999 ◽  
Vol 10 (3) ◽  
pp. 519-528
Author(s):  
BRUNO MOULIN ◽  
SOPHIE DERET ◽  
XAVIER MARIETTE ◽  
OLIVIER KOURILSKY ◽  
HIROKAZU IMAI ◽  
...  
Keyword(s):  
Heavy Chain ◽  
Plasma Cells ◽  
Apparent Molecular Weight ◽  
Light Chains ◽  
Monoclonal Immunoglobulin ◽  
Heavy Chains ◽  
Nodular Glomerulosclerosis ◽  
Heavy Chain Deposition Disease ◽  
Serum Fractionation

Abstract. The objective of this study was to further characterize the clinical and immunopathologic features of heavy chain deposition disease (HCDD), a recently described entity. Four patients were diagnosed as having HCDD on a kidney biopsy. All presented with nodular glomerulosclerosis with deposition of γ1 heavy chains lacking CH1 epitopes, but without light chains. Two different patterns were observed in the serum. First, patients 1 and 2 had a circulating monoclonal IgGλ containing a short γ1 heavy chain lacking CH1 epitopes, with an apparent molecular weight of 40 kD consistent with a complete CH1 deletion. Biosynthetic experiments also showed that the deleted heavy chain was produced in excess compared with light chains, and was secreted in vitro together with half Ig molecules, although these abnormal components were not detected by Western blot analysis of whole serum. Second, patients 3 and 4 had a circulating monoclonal IgG1λ with an apparently normal, nondeleted heavy chain subunit, but serum fractionation followed by immunoblotting revealed an isolated monoclonal γ1 chain lacking CH1 epitopes. These data strongly suggest that renal deposition of a CH1-deleted heavy chain circulating in low amounts in the serum as a free unassembled subunit is a major feature of HCDD. The CH1 deletion is most likely responsible for the premature secretion in blood of the heavy chain by a clone of plasma cells.

Activation of a selective pathway of lysosomal proteolysis in rat liver by prolonged starvation

1995 ◽  
Vol 269 (5) ◽  
pp. C1200-C1208 ◽  
Author(s):  
A. M. Cuervo ◽  
E. Knecht ◽  
S. R. Terlecky ◽  
J. F. Dice
Keyword(s):  
Rat Liver ◽  
Ribonuclease A ◽  
Rnase A ◽  
Immunogold Labeling ◽  
Prolonged Starvation ◽  
Lysosomal Proteolysis ◽  
Heat Shock Cognate Protein ◽  
Cognate Protein

Lysosomal uptake and degradation of polypeptides such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH), ribonuclease A (RNase A), and RNase S-peptide (residues 1-20 of RNase A) are progressively activated in rat liver by starvation before isolation of lysosomes. This pathway of proteolysis is selective, since it is stimulated by the heat shock cognate protein of 73 kDa (HSC73) and ATP-MgCl2, and lysosomal uptake of RNase A could be competed by GAPDH but not by ovalbumin. A portion of intracellular HSC73 is associated with certain lysosomes, and the amount of lysosomal HSC73 increases by 5- to 10-fold during prolonged starvation. The lysosome-associated HSC73 is primarily within the lysosomal lumen. Double immunogold labeling of lysosomes incubated in vitro with RNase A detects this protein substrate as well as HSC73 within lysosomes. More than two-thirds of the labeled lysosomes contain both RNase A and HSC73. The possible physiological significance of the activation of this selective pathway of lysosomal proteolysis in long-term starvation is discussed.

scholarly journals Characterization of non-heme iron aliphatic halogenase WelO5* from Hapalosiphon welwitschii IC-52-3: Identification of a minimal protein sequence motif that confers enzymatic chlorination specificity in the biosynthesis of welwitindolelinones

2017 ◽  
Vol 13 ◽  
pp. 1168-1173 ◽  
Author(s):  
Qin Zhu ◽  
Xinyu Liu
Keyword(s):  
Biochemical Characterization ◽  
Structural Diversity ◽  
Heme Iron ◽  
Sequence Motif ◽  
Rational Engineering ◽  
Non Heme Iron ◽  
C Terminus ◽  
Signature Sequence

The in vitro biochemical characterization revealed that iron/2-oxoglutarate (Fe/2OG)-dependent aliphatic halogenase WelO5* in Hapalosiphon welwitschii IC-52-3 has an enhanced substrate specificity towards 12-epi-hapalindole C (1) in comparison to WelO5 in H. welwitschii UTEX B1830. This allowed us to define the origin of the varied chlorinated versus dechlorinated alkaloid structural diversity between the two welwitindolinone producers. Furthermore, this study, along with the recent characterization of the AmbO5 protein, collectively confirmed the presence of a signature sequence motif in the C-terminus of this newly discovered halogenase enzyme family that confers substrate promiscuity and specificity. These observations may guide the rational engineering and evolution of these proteins for biocatalyst application.

An Atypical Human Immunoglobulin G with Deletions in both Heavy and Light Chains. Studies of the Conformation and the In Vitro Recombination of the Isolated Subunits

1974 ◽  
Vol 52 (7) ◽  
pp. 610-619 ◽  
Author(s):  
M. E. Percy ◽  
K. J. Dorrington
Keyword(s):  
Heavy Chain ◽  
Light Chain ◽  
Hypervariable Region ◽  
Light Chains ◽  
Constant Region ◽  
Myeloma Protein ◽  
Variable Regions ◽  
Heavy Chains ◽  
Amino Terminal

Both the light and gamma (heavy) chains of IgG(Sac) contain extensive deletions in their variable regions. The deletion in the light chain is internal (residues 18–88), whereas the deletion in the heavy chain is amino-terminal (residues 1–102). The hypervariable region just preceding the beginning of the constant region in other heavy chains (residues 103–115) is amino-terminal in heavy chain(Sac). In 4 mM acetate, pH 5.4, heavy chain(Sac) is dimeric like normal gamma chains, whereas light chain(Sac) is monomeric. Isolated light and heavy chains of IgG(Sac) recombine in vitro with each other and also with the heavy and light chains from a typical human IgG1-K myeloma protein, but not in a fashion entirely typical of other human gamma and light chains. These studies support the concept that non-covalent forces between the variable regions of the light and heavy chains are important in the assembly of the immunoglobulin molecule; and in view of the weak interaction between the constant region of light chain and heavy chain observed previously, our data suggest that there are points of contact between the hypervariable region of the gamma chain (residues 103–115) and the variable region of the light chain.

scholarly journals BiP and Immunoglobulin Light Chain Cooperate to Control the Folding of Heavy Chain and Ensure the Fidelity of Immunoglobulin Assembly

1999 ◽  
Vol 10 (7) ◽  
pp. 2209-2219 ◽  
Author(s):  
Young-Kwang Lee ◽  
Joseph W. Brewer ◽  
Rachel Hellman ◽  
Linda M. Hendershot
Keyword(s):  
Heavy Chain ◽  
Light Chain ◽  
Protein Complexes ◽  
Critical Role ◽  
Light Chains ◽  
Heavy Chains ◽  
Chain Complexes ◽  
Chain Synthesis

The immunoglobulin (Ig) molecule is composed of two identical heavy chains and two identical light chains (H2L2). Transport of this heteromeric complex is dependent on the correct assembly of the component parts, which is controlled, in part, by the association of incompletely assembled Ig heavy chains with the endoplasmic reticulum (ER) chaperone, BiP. Although other heavy chain-constant domains interact transiently with BiP, in the absence of light chain synthesis, BiP binds stably to the first constant domain (CH1) of the heavy chain, causing it to be retained in the ER. Using a simplified two-domain Ig heavy chain (VH-CH1), we have determined why BiP remains bound to free heavy chains and how light chains facilitate their transport. We found that in the absence of light chain expression, the CH1 domain neither folds nor forms its intradomain disulfide bond and therefore remains a substrate for BiP. In vivo, light chains are required to facilitate both the folding of the CH1 domain and the release of BiP. In contrast, the addition of ATP to isolated BiP–heavy chain complexes in vitro causes the release of BiP and allows the CH1 domain to fold in the absence of light chains. Therefore, light chains are not intrinsically essential for CH1 domain folding, but play a critical role in removing BiP from the CH1 domain, thereby allowing it to fold and Ig assembly to proceed. These data suggest that the assembly of multimeric protein complexes in the ER is not strictly dependent on the proper folding of individual subunits; rather, assembly can drive the complete folding of protein subunits.

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