Protein degradation by the phosphoinositide-specific phospholipase C-alpha family from rat liver endoplasmic reticulum.
A 60-kDa protein homologous to phosphoinositide-specific phospholipase C-alpha was purified to apparent homogeneity on sodium dodecyl sulfate-polyacrylamide gel electrophoresis from the rough endoplasmic reticulum of rat liver through three sequential chromatographies on DEAE Toyopearl 650, AF-heparin Toyopearl 650M, and TSK gel G3000SW. The purified protein was monomeric, with an M(r) of 60,000. Eight types of protein were further separated from the 60-kDa protein and named ER60A-ER60H according to the order of their elution from a TSK gel DEAE-5PW column. They were essentially identical in terms of immunochemical properties and the NH2-terminal amino acid sequence. The partial amino acid sequence of ER60F showed homology to that of phosphoinositide-specific phospholipase C-alpha. ER60A-ER60H showed no phosphoinositide-specific phospholipase C activity. However, ER60A-ER60H catalyzed cleavage of themselves and the endoplasmic reticulum proteins protein disulfide-isomerase and calreticulin. Proteolytic degradation was inhibited by p-chloromercuribenzoate. These results indicate that ER60A-ER60H comprise a group of endoplasmic reticulum resident proteins and show thiol group-related proteolytic activity.
Urade
R
R
Research Institute for Food Science, Kyoto University, Japan.
Nasu
M
M
Moriyama
T
T
Wada
K
K
Kito
M
M
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002853:Chromatography, Liquid; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D008099:Liver / Q000201:enzymology* / Q000648:ultrastructure; D008297:Male; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010727:Phosphoric Diester Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D010727:Phosphoric Diester Hydrolases; D043265:Phosphatidylinositol Diacylglycerol-Lyase