Molecular cloning and cellular localization of a BiP homologue in Trypanosoma brucei. Divergent ER retention signals in a lower eukaryote

摘要: Using the polymerase chain reaction with degenerate primers, three new members of hsp70 gene family Trypanosoma brucei have been identified. A genomic clone one these, gA, has fully sequenced and corresponding product characterized using antibody to recombinant gA fusion protein. is trypanosomal homologue BiP, an endoplasmic reticulum resident member, based on four lines evidence: (1) protein 64% deduced amino acid identity rat BiP; (2) sequence a putative secretory signal peptide; (3) soluble luminal microsome fraction; (4) polypeptide does not cofractionate mitochondrial markers. Trypanosomes are most primitive eukaryote yet in which BiP The used as specific marker for direct visualization trypanosomes by both indirect immunofluorescence cryoimmuno electron microscopy. seen tubular network that extends throughout cell excluding flagellum. C-terminal tetrapeptide MDDL, which, together (KQDL) trypanosome disulfide isomerase (Hsu et al. (1989) Biochemistry 28, 6440-6446), indicates retrieval signals may be divergent heterogeneous any other eukaryotes studied.