| First Author | Cala SE | Year | 1994 |
| Journal | J Biol Chem | Volume | 269 |
| Issue | 8 | Pages | 5926-31 |
| PubMed ID | 8119936 | Mgi Jnum | J:16953 |
| Mgi Id | MGI:65010 | Doi | 10.1016/s0021-9258(17)37550-6 |
| Citation | Cala SE, et al. (1994) GRP94 resides within cardiac sarcoplasmic reticulum vesicles and is phosphorylated by casein kinase II. J Biol Chem 269(8):5926-31 |
| abstractText | Cardiac sarcoplasmic reticulum (SR) plays a dominant role in cellular Ca2+ homeostasis by storing and releasing Ca2+. SDS-polyacrylamide gel electrophoresis and Stains All staining reveals that at least six Ca(2+)-binding proteins are contained in cardiac SR vesicles, five of which have now been identified. These five SR proteins comprise a set of high capacity Ca(2+)-binding proteins, localized to the SR lumen, that exhibit properties expected for physiological Ca2+ stores. In this study, we have purified and isolated cDNA clones for the sixth major Stains All blue-staining protein of dog cardiac SR and identified it as GRP94 (glucose-regulated protein, M(r) = 94,000). Previously, this prominent Ca(2+)-binding component has only been described in non-muscle endoplasmic reticulum. Cardiac GRP94 co-sedimented with cardiac SR vesicles and all previously described SR markers and was completely contained within the SR lumen. GRP94, like several other SR Ca(2+)-binding proteins, was a substrate for casein kinase II and was phosphorylated at two or more sites located near the two ends of the molecule. A low level of endogenous casein kinase II activity was found in crude preparations of cardiac SR but did not co-purify with SR vesicles after calcium oxalate loading, suggesting that casein kinase II phosphorylation in vivo occurs at a site other than the SR. |
