| First Author | Hata S | Year | 2007 |
| Journal | J Biol Chem | Volume | 282 |
| Issue | 38 | Pages | 27847-56 |
| PubMed ID | 17646163 | Mgi Jnum | J:125385 |
| Mgi Id | MGI:3758398 | Doi | 10.1074/jbc.M703168200 |
| Citation | Hata S, et al. (2007) Stomach-specific calpain, nCL-2/calpain 8, is active without calpain regulatory subunit and oligomerizes through C2-like domains. J Biol Chem 282(38):27847-56 |
| abstractText | Calpains constitute a family of intracellular Ca(2+)-regulated cysteine proteases that are indispensable in the regulation of a wide variety of cellular functions. The improper activation of calpain causes lethality or various disorders, such as muscular dystrophies and tumor formation. nCL-2/calpain 8 is predominantly expressed in the stomach, where it appears to be involved in membrane trafficking in the gastric surface mucus cells (pit cells). Although the primary structure of nCL-2 is quite similar to that of the ubiquitous m-calpain large subunit, the enzymatic properties of nCL-2 have never been reported. Here, to characterize nCL-2, the recombinant protein was prepared using an Escherichia coli expression system and purified to homogeneity. nCL-2 was stably produced as a soluble and active enzyme without the conventional calpain regulatory subunit (30K). Purified nCL-2 showed Ca(2+)-dependent activity, with half-maximal activity at about 0.3 mM Ca(2+), similar to that of m-calpain, whereas its optimal pH and temperature were comparatively low. Immunoprecipitation analysis revealed that nCL-2 exists in both monomeric and homo-oligomeric forms, but not as a heterodimer with 30K or 30K-2, and that the oligomerization occurs through domains other than the 5EF-hand domain IV, most probably through domain III, suggesting a novel regulatory system for nCL-2. |
