title: Rab39, a novel Golgi-associated Rab GTPase from human dendritic cells involved in cellular endocytosis.
abstract: Rab GTPases are Ras-like small molecular weight GTP binding proteins that are involved in various steps along the exocytic and endocytic pathways. Here we report that Rab39, a novel Rab protein, is a Golgi-associated protein involved in endocytosis of HeLa cells. Full-length cDNA of Rab39 contains 1251bp with an open reading frame (ORF) of 636bp, which is predicted to encode a 211 aa protein. By blast analysis of Rab39 cDNA and protein sequence with homologues, we find that Rab39 may be a short variant of Rab34. Rab39 contains conserved motifs involved in phosphate/guanosine binding and a microbody C-terminal targeting signal. RT-PCR analysis indicates that Rab39 is mainly detected in epithelial cell lines, and Northern blot analysis shows that Rab39 is expressed ubiquitously in human tissues. By using FITC-BSA as an endocytic tracer, we show that Rab39 can facilitate endocytosis in HeLa cells when expressed either transiently or stably. Confocal microscopy examination of Rab39 subcellular localization suggests that Rab39 is associated with Golgi-associated organelles. Our findings demonstrate that Rab39 is a novel Rab GTPase involved in cellular endocytosis.
authors.affiliation: Institute of Immunology, Second Military Medical University, 800 Xiangyin Road, Shanghai 200433, PR China.
authors.forename: Taoyong
authors.initials: T
authors.lastname: Chen
authors.forename: Yanmei
authors.initials: Y
authors.lastname: Han
authors.forename: Mingjin
authors.initials: M
authors.lastname: Yang
authors.forename: Weiping
authors.initials: W
authors.lastname: Zhang
authors.forename: Nan
authors.initials: N
authors.lastname: Li
authors.forename: Tao
authors.initials: T
authors.lastname: Wan
authors.forename: Jun
authors.initials: J
authors.lastname: Guo
authors.forename: Xuetao
authors.initials: X
authors.lastname: Cao
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003713:Dendritic Cells / Q000201:enzymology*; D004705:Endocytosis; D006056:Golgi Apparatus / Q000201:enzymology*; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000096:biosynthesis; D016415:Sequence Alignment; D020691:rab GTP-Binding Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*
chemical_list: D012333:RNA, Messenger; C474116:RAB39A protein, human; D020691:rab GTP-Binding Proteins