Pancreas specific protein disulfide isomerase, PDIp, is in transient contact with secretory proteins during late stages of translocation.
Protein disulfide isomerase (PDI) and an additional lumenal protein of dog pancreas microsomes were previously observed to be in transient contact with secretory proteins during late stages of their co- or posttranslational translocation into these mammalian microsomes. The second protein was characterized as a 57 kDa glycoprotein. Here we identified this glycoprotein as the canine equivalent of human PDIp, a protein which was recently described as a new protein disulfide isomerase which is highly expressed in human pancreas. Canine PDIp is also a very abundant protein, its concentration in pancreatic microsomes approaches the concentration of PDI and of the major microsomal molecular chaperones. Apparently, PDIp shares with PDI not just the enzymatic but also the polypeptide binding or chaperoning activity. Furthermore, we suggest that PDIp, too, can be involved in completion of cotranslational as well as posttranslational translocation of proteins into mammalian microsomes.
Volkmer
J
J
Medizinische Biochemie, Universität des Saarlandes, Homburg, Germany.
Guth
S
S
Nastainczyk
W
W
Knippel
P
P
Klappa
P
P
Gnau
V
V
Zimmermann
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D004285:Dogs; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006801:Humans; D007301:Insect Hormones / Q000378:metabolism; D019476:Insect Proteins; D007535:Isomerases / Q000737:chemistry / Q000378:metabolism*; D008861:Microsomes / Q000201:enzymology; D018832:Molecular Chaperones / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010179:Pancreas / Q000201:enzymology* / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism; D014176:Protein Biosynthesis; D019704:Protein Disulfide-Isomerases; D011498:Protein Precursors / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism
C059037:CecA2 protein, Bombyx mori; D007301:Insect Hormones; D019476:Insect Proteins; D018832:Molecular Chaperones; D011498:Protein Precursors; D011506:Proteins; D011994:Recombinant Proteins; C017671:preprolactin; D011388:Prolactin; D013762:Tetrahydrofolate Dehydrogenase; D007535:Isomerases; D019704:Protein Disulfide-Isomerases