Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10926523 | Cell Calcium | 2005 | 8 Pages |
Abstract
Alternative splicing of the sarco/endoplasmic reticulum (SERCA2) Ca2+ pump transcript generates the two isoforms: SERCA2a in left ventricular myocytes (LVM) and SERCA2b in most tissues. Nuclear protein extracts from left ventricular myocytes can cause a decay of the 3â²-region of the SERCA2a. To determine if all the domains in the 800 b SERCA2a 3â²-end region (3344-4243) are equally stable, we examined in vitro decay of synthetically capped, polyadenylated overlapping RNA fragments 2A1-2A6 from the 3â²-end region of SERCA2a. Whereas 2A1-2A5 RNAs were stable, the distal fragment 2A6 (4135-4243 b) decayed rapidly. Deleting the 2A6 sequence from the 800-b 3â²-end region increased its stability. In mobility shift assays, 2A6 bound to protein(s) in the LVM nuclear extracts in a specific manner: unlabelled 2A6 or the 800 b 3â²-region RNA competed for binding but poly A, poly U, and poly C RNA did not. Secondary structure analysis revealed three hairpin loops in 2A6. Experiments using small synthetic RNA fragments for competition with 2A6 binding to nuclear proteins were consistent with a model involving the three hairpin loops. Thus, the secondary structure of the distal domain of SERCA2a RNA may be important in regulating its stability.
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Authors
Christine M. Misquitta, Paromita Ghosh, James Mwanjewe, Ashok K. Grover,