Sorcin (SRI)

The 22-kD sorcin protein was overexpressed in HOB1/VCR-1.0 cells, a multidrug-resistant human B immunoblastic lymphoma cell line. By PCR with primers based on the sequence of hamster sorcin, the authors recovered a partial human sorcin cDNA. Using the partial cDNA to screen a HOB1/VCR-1.0 library, they isolated cDNAs corresponding to the entire sorcin coding region. The predicted 198-amino acid human protein shares 95% sequence identity with hamster sorcin.

Human sorcin contains 4 EF-hand calcium-binding motifs. Purified protein bound calcium in vitro. Southern and Northern blot analysis revealed that the sorcin gene is amplified and overexpressed in HOB1/VCR-1.0 cells. No expression was detected in parental HOB1 cells.