PMID- 10359607 OWN - NLM STAT- MEDLINE DCOM- 19990729 LR - 20181113 IS - 1059-1524 (Print) IS - 1059-1524 (Linking) VI - 10 IP - 6 DP - 1999 Jun TI - Localization and recycling of gp27 (hp24gamma3): complex formation with other p24 family members. PG - 1939-55 AB - We report here the characterization of gp27 (hp24gamma3), a glycoprotein of the p24 family of small and abundant transmembrane proteins of the secretory pathway. Immunoelectron and confocal scanning microscopy show that at steady state, gp27 localizes to the cis side of the Golgi apparatus. In addition, some gp27 was detected in COPI- and COPII-coated structures throughout the cytoplasm. This indicated cycling that was confirmed in three ways. First, 15 degrees C temperature treatment resulted in accumulation of gp27 in pre-Golgi structures colocalizing with anterograde cargo. Second, treatment with brefeldin A caused gp27 to relocate into peripheral structures positive for both KDEL receptor and COPII. Third, microinjection of a dominant negative mutant of Sar1p trapped gp27 in the endoplasmic reticulum (ER) by blocking ER export. Together, this shows that gp27 cycles extensively in the early secretory pathway. Immunoprecipitation and coexpression studies further revealed that a significant fraction of gp27 existed in a hetero-oligomeric complex. Three members of the p24 family, GMP25 (hp24alpha2), p24 (hp24beta1), and p23 (hp24delta1), coprecipitated in what appeared to be stochiometric amounts. This heterocomplex was specific. Immunoprecipitation of p26 (hp24gamma4) failed to coprecipitate GMP25, p24, or p23. Also, very little p26 was found coprecipitating with gp27. A functional requirement for complex formation was suggested at the level of ER export. Transiently expressed gp27 failed to leave the ER unless other p24 family proteins were coexpressed. Comparison of attached oligosaccharides showed that gp27 and GMP25 recycled differentially. Only a very minor portion of GMP25 displayed complex oligosaccharides. In contrast, all of gp27 showed modifications by medial and trans enzymes at steady state. We conclude from these data that a portion of gp27 exists as hetero-oligomeric complexes with GMP25, p24, and p23 and that these complexes are in dynamic equilibrium with individual p24 proteins to allow for differential recycling and distributions. FAU - Fullekrug, J AU - Fullekrug J AD - Cell Biology and Cell Biophysics Program, European Molecular Biology Laboratory, 69117 Heidelberg, Germany. FAU - Suganuma, T AU - Suganuma T FAU - Tang, B L AU - Tang BL FAU - Hong, W AU - Hong W FAU - Storrie, B AU - Storrie B FAU - Nilsson, T AU - Nilsson T LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't PT - Research Support, U.S. Gov't, P.H.S. PL - United States TA - Mol Biol Cell JT - Molecular biology of the cell JID - 9201390 RN - 0 (Carrier Proteins) RN - 0 (Fungal Proteins) RN - 0 (G protein, vesicular stomatitis virus) RN - 0 (Glycoproteins) RN - 0 (KDEL receptor) RN - 0 (LMAN1 protein, human) RN - 0 (Mannose-Binding Lectins) RN - 0 (Membrane Glycoproteins) RN - 0 (Membrane Proteins) RN - 0 (Nuclear Pore Complex Proteins) RN - 0 (Oligosaccharides) RN - 0 (Phosphoproteins) RN - 0 (Receptors, Peptide) RN - 0 (Recombinant Proteins) RN - 0 (SEC13 protein, S cerevisiae) RN - 0 (SEC31 protein, S cerevisiae) RN - 0 (Saccharomyces cerevisiae Proteins) RN - 0 (Vesicular Transport Proteins) RN - 0 (Viral Envelope Proteins) RN - 20350-15-6 (Brefeldin A) RN - EC 3.6.1.- (GTP-Binding Proteins) RN - EC 3.6.5.2 (Monomeric GTP-Binding Proteins) RN - EC 3.6.5.2 (SAR1 protein, S cerevisiae) SB - IM MH - Amino Acid Sequence MH - Biological Transport MH - Brefeldin A/pharmacology MH - Carrier Proteins/metabolism MH - Endoplasmic Reticulum/drug effects/metabolism MH - Fungal Proteins/metabolism MH - GTP-Binding Proteins/metabolism MH - Glycoproteins/metabolism MH - Glycosylation MH - Golgi Apparatus/drug effects/*metabolism/ultrastructure MH - Humans MH - *Mannose-Binding Lectins MH - Membrane Glycoproteins/genetics/*metabolism MH - Membrane Proteins/metabolism MH - Molecular Sequence Data MH - *Monomeric GTP-Binding Proteins MH - Nuclear Pore Complex Proteins MH - Oligosaccharides/metabolism MH - Phosphoproteins/metabolism MH - Receptors, Peptide/metabolism MH - Recombinant Proteins/genetics/metabolism MH - *Saccharomyces cerevisiae Proteins MH - Vesicular Transport Proteins MH - Viral Envelope Proteins/metabolism PMC - PMC25391 EDAT- 1999/06/08 00:00 MHDA- 1999/06/08 00:01 CRDT- 1999/06/08 00:00 PHST- 1999/06/08 00:00 [pubmed] PHST- 1999/06/08 00:01 [medline] PHST- 1999/06/08 00:00 [entrez] AID - 10.1091/mbc.10.6.1939 [doi] PST - ppublish SO - Mol Biol Cell. 1999 Jun;10(6):1939-55. doi: 10.1091/mbc.10.6.1939.