A Novel Human Rab26 cDNA Coloning, Expression and Its Endocytosis Enhancing Function

Rab GTPases serve as master regulators of vesicular membrane transport on both the exo- and endocytic pathways. Though there are many reports on Rab proteins, the function of these small proteins still remain in speculation. And no report has ever clarified the character of human Rab26. Here it was reported that a novel Rab protein Rab26 is membranous organelle related and involved in endocytosis of HeLa cells. By using RT-PCR method a novel Rab26 cDNA full-length cDNA of Rab26 that is 1656 bp was identified. The cDNA sequence that at 1197 is‘A’other than‘G’, while‘C’at 956 substitutes for‘T’, and has‘GCC’insertion at 48 to 50 compared with published sequences. The complete open reading frame (ORF) is 771 bp in length encoding 256-residue protein with a calculated molecular mass of 27.9 ku (GenBank accession No.AY646153), rather than a shorter one with 190-amino acid residue as reported previously. GFP labeled full-length Rab26 expression showed that Rab26 was mainly sublocated in membranous organelles and could enhance endocytosis which means could took PE labeled protein as an endocytic tracer. RT-PCR analysis showed Rab26 was detected to express in several kinds of adenocarcinoma cell lines such as Acc2, AccM, SPC-A1 and HeLa cell lines, which indicated that Rab26 expression might be associated with some carcinomas.