Alternative Splicing of the HumanRab6AGene Generates Two Close but Functionally Different Isoforms

Analysis of the human Rab6A gene structure reveals the presence of a duplicated exon, and incorporation of either of the two exons by alternative splicing is shown to generate two Rab6 isoforms named Rab6A and Rab6A′, which differ in only three amino acid residues located in regions flanking the PM3 GTP-binding domain of the proteins. These isoforms are ubiquitously expressed at similar levels, exhibit the same GTP-binding properties, and are localized to the Golgi apparatus. Overexpression of the GTP-bound mutants of Rab6A (Rab6A Q72L) or Rab6A′ (Rab6A′ Q72L) inhibits secretion in HeLa cells, but overexpression of Rab6A′ Q72L does not induce the redistribution of Golgi proteins into the endoplasmic reticulum. This suggests that Rab6A′ is not able to stimulate Golgi-to-endoplasmic reticulum retrograde transport, as described previously for Rab6A. In addition, Rab6A′ interacts with two Rab6A partners, GAPCenA and “clone 1,” but not with the kinesin-like protein Rabkinesin-6, a Golgi-associated Rab6A effector. Interestingly, we found that the functional differences between Rab6A and Rab6A′ are contingent on one amino acid (T or A at position 87). Therefore, limited amino acid substitutions within a Rab protein introduced by alternative splicing could represent a mechanism to generate functionally different isoforms that interact with distinct sets of effectors.

Download Full-text

Protein truncation is required for the activation of the c-myb proto-oncogene

Molecular and Cellular Biology ◽

10.1128/mcb.11.8.3987-3996.1991 ◽

1991 ◽

Vol 11 (8) ◽

pp. 3987-3996

Author(s):

F A Grässer ◽

T Graf ◽

J S Lipsick

Keyword(s):

Amino Acid ◽

Bone Marrow Cells ◽

Protein Product ◽

Full Length ◽

Carboxyl Terminus ◽

Amino Acid Substitutions ◽

Amino Acid Residues ◽

Avian Myeloblastosis Virus ◽

Virally Encoded ◽

Myb Proteins

The protein product of the v-myb oncogene of avian myeloblastosis virus, v-Myb, differs from its normal cellular counterpart, c-Myb, by (i) expression under the control of a strong viral long terminal repeat, (ii) truncation of both its amino and carboxyl termini, (iii) replacement of these termini by virally encoded residues, and (iv) substitution of 11 amino acid residues. We had previously shown that neither the virally encoded termini nor the amino acid substitutions are required for transformation by v-Myb. We have now constructed avian retroviruses that express full-length or singly truncated forms of c-Myb and have tested them for the transformation of chicken bone marrow cells. We conclude that truncation of either the amino or carboxyl terminus of c-Myb is sufficient for transformation. In contrast, the overexpression of full-length c-Myb does not result in transformation. We have also shown that the amino acid substitutions of v-Myb by themselves are not sufficient for the activation of c-Myb. Rather, the presence of either the normal amino or carboxyl terminus of c-Myb can suppress transformation when fused to v-Myb. Cells transformed by c-Myb proteins truncated at either their amino or carboxyl terminus appear to be granulated promyelocytes that express the Mim-1 protein. Cells transformed by a doubly truncated c-Myb protein are not granulated but do express the Mim-1 protein, in contrast to monoblasts transformed by v-Myb that neither contain granules nor express Mim-1. These results suggest that various alterations of c-Myb itself may determine the lineage of differentiating hematopoietic cells.

Download Full-text

Application of heptapeptides containing D-amino acid residues immobilized to magnetic particles and Sepharose for the study of binding properties of gastric aspartic proteases

Journal of Separation Science ◽

10.1002/jssc.201200221 ◽

2012 ◽

Vol 35 (15) ◽

pp. 1899-1905 ◽

Cited By ~ 6

Author(s):

Michaela Rajčanová ◽

Marie Tichá ◽

Zdenka Kučerová

Keyword(s):

Amino Acid ◽

Magnetic Particles ◽

Amino Acid Residues ◽

Binding Properties ◽

Aspartic Proteases

Download Full-text

Mycoplasma pneumoniae Community-Acquired Respiratory Distress Syndrome Toxin Uses a Novel KELED Sequence for Retrograde Transport and Subsequent Cytotoxicity

mBio ◽

10.1128/mbio.01663-17 ◽

2018 ◽

Vol 9 (1) ◽

Cited By ~ 4

Author(s):

Kumaraguruparan Ramasamy ◽

Sowmya Balasubramanian ◽

Krishnan Manickam ◽

Lavanya Pandranki ◽

Alexander B. Taylor ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Amino Acid ◽

Mycoplasma Pneumoniae ◽

Retrograde Transport ◽

Airway Disease ◽

The United States ◽

Community Acquired Pneumonia ◽

Trauma Patients ◽

Airway Injury ◽

Cards Toxin

ABSTRACTMycoplasma pneumoniaeis an atypical bacterium that causes respiratory illnesses in humans, including pharyngitis, tracheobronchitis, and community-acquired pneumonia (CAP). It has also been directly linked to reactive airway disease, asthma, and extrapulmonary pathologies. During its colonization,M. pneumoniaeexpresses a unique ADP-ribosylating and vacuolating cytotoxin designatedcommunity-acquiredrespiratorydistresssyndrome (CARDS) toxin. CARDS toxin persists and localizes in the airway in CAP patients, asthmatics, and trauma patients with ventilator-associated pneumonia. Although CARDS toxin binds to specific cellular receptors, is internalized, and induces hyperinflammation, histopathology, mucus hyperplasia, and other airway injury, the intracellular trafficking of CARDS toxin remains unclear. Here, we show that CARDS toxin translocates through early and late endosomes and the Golgi complex and concentrates at the perinuclear region to reach the endoplasmic reticulum (ER). Using ER-targeted SNAP-tag, we confirmed the association of CARDS toxin with the ER and determined that CARDS toxin follows the retrograde pathway. In addition, we identified a novel CARDS toxin amino acid fingerprint, KELED, that is required for toxin transport to the ER and subsequent toxin-mediated cytotoxicity.IMPORTANCEMycoplasma pneumoniae, a leading cause of bacterial community-acquired pneumonia (CAP) among children and adults in the United States, synthesizes a 591-amino-acid ADP-ribosylating and vacuolating protein, designatedcommunity-acquiredrespiratorydistresssyndrome (CARDS) toxin. CARDS toxin alone is sufficient to induce and mimic major inflammatory and histopathological phenotypes associated withM. pneumoniaeinfection in rodents and primates. In order to elicit its ADP-ribosylating and vacuolating activities, CARDS toxin must bind to host cell receptors, be internalized via clathrin-mediated pathways, and subsequently be transported to specific intracellular organelles. Here, we demonstrate how CARDS toxin utilizes its unique KELED sequence to exploit the retrograde pathway machinery to reach the endoplasmic reticulum (ER) and fulfill its cytopathic potential. The knowledge generated from these studies may provide important clues to understand the mode of action of CARDS toxin and develop interventions that reduce or eliminateM. pneumoniae-associated airway and extrapulmonary pathologies.

Download Full-text

Amino acid residues conferring the nucleotide binding properties of N-acetyl-D-glucosamine 2-epimerase (renin binding protein)

Biomedical Research ◽

10.2220/biomedres.26.117 ◽

2005 ◽

Vol 26 (3) ◽

pp. 117-121 ◽

Cited By ~ 4

Author(s):

Saori TAKAHASHI ◽

Hironobu OGASAWARA ◽

Kazuyuki HIWATASHI ◽

Keishi HATA ◽

Kazuyuki HORI ◽

...

Keyword(s):

Amino Acid ◽

Binding Protein ◽

Nucleotide Binding ◽

Amino Acid Residues ◽

Binding Properties

Download Full-text

Effect of single amino acid substitutions in the hemagglutinin on the receptor-binding properties of influenza B viruses

Journal of Clinical Virology ◽

10.1016/j.jcv.2015.07.074 ◽

2015 ◽

Vol 70 ◽

pp. S29

Author(s):

E. Sorokin ◽

T. Tsareva ◽

A. Sominina ◽

M. Pisareva ◽

A. Komissarov ◽

...

Keyword(s):

Amino Acid ◽

Receptor Binding ◽

Single Amino Acid ◽

Influenza B ◽

Amino Acid Substitutions ◽

Binding Properties

Download Full-text

rasH mutants deficient in GTP binding.

Molecular and Cellular Biology ◽

10.1128/mcb.6.9.3291 ◽

1986 ◽

Vol 6 (9) ◽

pp. 3291-3294 ◽

Cited By ~ 65

Author(s):

C J Der ◽

B T Pan ◽

G M Cooper

Keyword(s):

Amino Acid ◽

Binding Affinity ◽

Binding Proteins ◽

Single Amino Acid ◽

Amino Acid Substitutions ◽

3T3 Cells ◽

Protein Residues ◽

Gtp Binding ◽

Nih 3T3 ◽

P21 Proteins

Single amino acid substitutions were introduced into a region of the rasH protein (residues 116, 117, and 119) homologous to a variety of diverse GTP-binding proteins. Each of the mutant p21 proteins displayed a significant reduction (10- to 5,000-fold) in GTP binding affinity. Activated rasH proteins deficient in GTP binding were unaltered in their ability to morphologically transform NIH 3T3 cells.

Download Full-text

Single Amino Acid Substitutions in Puroindoline-b Mutants Influence Lipid Binding Properties†

Biochemistry ◽

10.1021/bi062190h ◽

2007 ◽

Vol 46 (8) ◽

pp. 2260-2266 ◽

Cited By ~ 29

Author(s):

Luke A. Clifton ◽

Mitaben D. Lad ◽

Rebecca J. Green ◽

Richard A. Frazier

Keyword(s):

Amino Acid ◽

Lipid Binding ◽

Single Amino Acid ◽

Amino Acid Substitutions ◽

Binding Properties

Download Full-text

Septal Pore Cap Protein SPC18, Isolated from the Basidiomycetous Fungus Rhizoctonia solani, Also Resides in Pore Plugs

Eukaryotic Cell ◽

10.1128/ec.00125-08 ◽

2008 ◽

Vol 7 (10) ◽

pp. 1865-1873 ◽

Cited By ~ 21

Author(s):

Kenneth G. A. van Driel ◽

Arend F. van Peer ◽

Jan Grijpstra ◽

Han A. B. Wösten ◽

Arie J. Verkleij ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Amino Acid ◽

Rhizoctonia Solani ◽

Filamentous Fungi ◽

Signal Peptide ◽

Biochemical Composition ◽

Amino Acid Residues ◽

Terminal Sequence ◽

Basidiomycetous Fungus ◽

Central Pore

ABSTRACT The hyphae of filamentous fungi are compartmentalized by septa that have a central pore. The fungal septa and septum-associated structures play an important role in maintaining cellular and intrahyphal homeostasis. The dolipore septa in the higher Basidiomycota (i.e., Agaricomycotina) are associated with septal pore caps. Although the ultrastructure of the septal pore caps has been studied extensively, neither the biochemical composition nor the function of these organelles is known. Here, we report the identification of the glycoprotein SPC18 that was found in the septal pore cap-enriched fraction of the basidiomycetous fungus Rhizoctonia solani. Based on its N-terminal sequence, the SPC18 gene was isolated. SPC18 encodes a protein of 158 amino acid residues, which contains a hydrophobic signal peptide for targeting to the endoplasmic reticulum and has an N-glycosylation motif. Immunolocalization showed that SPC18 is present in the septal pore caps. Surprisingly, we also observed SPC18 being localized in some plugs. The data reported here strongly support the hypothesis that septal pore caps are derived from endoplasmic reticulum and are involved in dolipore plugging and, thus, contribute to hyphal homeostasis in basidiomycetous fungi.

Download Full-text