Characterization of pancreatic ERj3p, a homolog of yeast DnaJ-like protein Scj1p.
We have previously identified in the human EST sequence data base four overlapping clones that could be aligned with both a predicted protein sequence, deduced from the C. elegans genomic sequence, and partial amino acid sequences, obtained for a protein from canine pancreatic microsomes. We suggested that these proteins are homologs of yeast microsomal and DnaJ-like protein Scj1p and termed them ERj3p. Here we verified the predicted protein sequence of human ERj3p by sequence analysis of the corresponding cDNA. Multiple alignment of related sequences identified these proteins as true homologs of yeast Scj1p. Biochemical analysis of the canine protein characterized ERj3p as a soluble glycoprotein of the pancreatic endoplasmic reticulum. This pancreatic DnaJ-like protein was shown to interact with lumenal DnaK-like proteins, such as BiP. Furthermore, we found that ERj3p interacts with SDF2L1 protein that may be involved in protein O-glycosylation. We propose that ERj3p represents a cochaperone of DnaK-like chaperones of the mammalian endoplasmic reticulum and is involved in folding and maturation of newly synthesized proteins.
Bies
Christiane
C
Medizinische Biochemie and Molekularbiologie, Universität des Saarlandes, D-66421 Homburg, Germany.
Blum
Robert
R
Dudek
Johanna
J
Nastainczyk
Wolfgang
W
Oberhauser
Simone
S
Jung
Martin
M
Zimmermann
Richard
R
D000595:Amino Acid Sequence; D000818:Animals; D018076:DNA, Complementary / Q000235:genetics; D004285:Dogs; D004721:Endoplasmic Reticulum / Q000737:chemistry; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry; D051379:Mice; D008861:Microsomes / Q000737:chemistry; D008969:Molecular Sequence Data; D010179:Pancreas / Q000737:chemistry* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; C494648:DNAJB11 protein, human; C067634:SCJ1 protein, S cerevisiae; C422105:SDF2L1 protein, human