RAT-LIVER ENDOPLASMIC-RETICULUM PROTEIN-KINASES

1. Rat liver microsomal membranes were studied for the presence of pro tein kinases. Microsomal proteins solubilized with Triton X-100 were a nalyzed by means of ion exchange chromatography. 2. Protein kinase act ivity was detected in the column fractions using specific assays for c AMP-dependent protein kinase, cGMP-dependent protein kinase, protein k inase C, Ca2+/calmodulin-dependent protein kinase and casein kinases. 3. Fractions with protein kinase activity were further analyzed by SDS -polyacrylamide gel electrophoresis. 4. The results indicate that cAMP -dependent protein kinase type I and II, casein kinases I and II, prot ein kinase C proenzymes I and II and Ca2+/calmodulin kinase II are ass ociated with the membranes of endoplasmic reticulum (ER).