Nucleic Acids Research Advance Access published online on November 10, 2008
Nucleic Acids Research, doi:10.1093/nar/gkn800
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Molecular Biology |
A cytoplasmic variant of the KH-type splicing regulatory protein serves as a decay-promoting factor for phosphoglycerate kinase 2 mRNA in murine male germ cells
1Center for Research on Reproduction and Women's Health, University of Pennsylvania School of Medicine, 1310 Biomedical Research Building, 421 Curie Boulevard, Philadelphia, PA 19104-6080 and 2Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
* To whom correspondence should be addressed. Tel: 215 898 0144; Fax: 215 573 7627; Email: nhecht{at}mail.med.upenn.edu
Received August 25, 2008. Revised October 8, 2008. Accepted October 12, 2008.
Phosphoglycerate kinase 2 (PGK2) is a germ cell-specific protein whose mRNA is translationally regulated in the mammalian testis. Using RNA affinity chromatography with the 3'-untranslated region (UTR) of Pgk2 mRNA and adult testis extracts, several associated proteins including a novel isoform of the AU-rich element RNA-binding protein and KH-type splicing regulatory protein (KSRP) were identified. KSRP, a protein of 
75 kDa, is widely expressed in somatic and germ cells where it is primarily nuclear. In addition to the 75-kDa KSRP, a 52-kD KSRP, t-KSRP, is present in the cytoplasm of a subpopulation of germ cells. t-KSRP binds directly to a 93-nt sequence (designated the F1 region) of the 3'-UTR of the Pgk2 mRNA and destabilizes Pgk2 mRNA constructs in testis extracts and in transfected cells. We conclude that this testicular variant of the multifunctional nucleic acid–binding protein, KSRP, serves as a decay-promoting factor for Pgk2 mRNA in male germ cells.