HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 67/6/1936    most recent biolreprod.102.004093v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal My Folders Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Huang, Z. Articles by Vijayaraghavan, S. Search for Related Content PubMed PubMed Citation Articles by Huang, Z. Articles by Vijayaraghavan, S. Agricola Articles by Huang, Z. Articles by Vijayaraghavan, S.

Sperm PP12 Is Regulated by a Homologue of the Yeast Protein Phosphatase Binding Protein sds22¹

^a Biological Sciences Department, Kent State University, Kent, Ohio 44242 ^b California State University, Long Beach, California 90840 ^c Faculteit Geneeskunde, Katholieke Universiteit Leuven, Leuven, Belgium ^d Veterans Affairs Medical Center, Oregon Health Sciences University, Portland, Oregon 97201

Serine/threonine phosphatase PP12 is a testis-specific protein phosphatase isoform in spermatozoa. This enzyme appears to play a key role in motility initiation and stimulation. Catalytic activity of PP12 is higher in immotile compared with motile spermatozoa. Inhibition of PP12 activity causes both motility initiation and motility stimulation. Protein phosphatases, in general, are regulated by their binding proteins. The objective of this article is to understand the mechanisms by which PP12 is regulated, first by identifying its regulatory proteins. We had previously shown that a portion of bovine sperm PP12 is present in the cytosolic fraction of sperm sonicates. We purified PP12 from soluble bovine sperm extracts by immunoaffinity chromatography. Gel electrophoresis of the purified enzyme showed that it was complexed to a protein 43 M_r x 10^-3 in size. Microsequencing revealed that this protein is a mammalian homologue of sds22, which is a yeast PP1 binding protein. Phosphatase activity measurements showed that PP12 complexed to sds22 is catalytically inactive. The complex cannot be activated by limited proteolysis. The complex is unable to bind to microcystin sepharose. This suggests that sds22 may block the microcystin binding site in PP12. A proportion of PP12 in sperm extracts, which is presumably not complexed to sds22, is catalytically active. Fluorescence immunocytochemistry was used to determine the intrasperm localization of PP12 and sds22. Both proteins are present in the tail. They are also present in distinct locations in the head. Our data suggest that PP12 binding to sds22 inhibits its catalytic activity. Mechanisms regulating sds22 binding to PP12 are likely to be important in understanding the biochemical basis underlying development and regulation of sperm function.

¹ Supported by NIH grant R01 HD38520.

² Correspondence. FAX: 330 672 3713; svijayar{at}kent.edu

This article has been cited by other articles:

				R. Chakrabarti, D. Kline, J. Lu, J. Orth, S. Pilder, and S. Vijayaraghavan Analysis of Ppp1cc-Null Mice Suggests a Role for PP1gamma2 in Sperm Morphogenesis Biol Reprod, June 1, 2007; 76(6): 992 - 1001. [Abstract] [Full Text] [PDF]

				L. Pedelini, M. Marquina, J. Arino, A. Casamayor, L. Sanz, M. Bollen, P. Sanz, and M. A. Garcia-Gimeno YPI1 and SDS22 Proteins Regulate the Nuclear Localization and Function of Yeast Type 1 Phosphatase Glc7 J. Biol. Chem., February 2, 2007; 282(5): 3282 - 3292. [Abstract] [Full Text] [PDF]

				Z. Huang, P. R. Somanath, R. Chakrabarti, E. M. Eddy, and S. Vijayaraghavan Changes in Intracellular Distribution and Activity of Protein Phosphatase PP1{gamma}2 and Its Regulating Proteins in Spermatozoa Lacking AKAP4 Biol Reprod, February 1, 2005; 72(2): 384 - 392. [Abstract] [Full Text] [PDF]

				C. Hrabchak and S. Varmuza Identification of the Spermatogenic Zip Protein Spz1 as a Putative Protein Phosphatase-1 (PP1) Regulatory Protein That Specifically Binds the PP1c{gamma}2 Splice Variant in Mouse Testis J. Biol. Chem., August 27, 2004; 279(35): 37079 - 37086. [Abstract] [Full Text] [PDF]

				Z. Huang and S. Vijayaraghavan Increased Phosphorylation of a Distinct Subcellular Pool of Protein Phosphatase, PP1{gamma}2, During Epididymal Sperm Maturation Biol Reprod, February 1, 2004; 70(2): 439 - 447. [Abstract] [Full Text] [PDF]

				H. CEULEMANS and M. BOLLEN Functional Diversity of Protein Phosphatase-1, a Cellular Economizer and Reset Button Physiol Rev, January 1, 2004; 84(1): 1 - 39. [Abstract] [Full Text] [PDF]

				S. Mishra, P. R. Somanath, Z. Huang, and S. Vijayaraghavan Binding and Inactivation of the Germ Cell-Specific Protein Phosphatase PP1{gamma}2 by sds22 During Epididymal Sperm Maturation Biol Reprod, November 1, 2003; 69(5): 1572 - 1579. [Abstract] [Full Text] [PDF]

				D. M. Katschinski, H. H. Marti, K. F. Wagner, J. Shibata, K. Eckhardt, F. Martin, R. Depping, U. Paasch, M. Gassmann, B. Ledermann, et al. Targeted Disruption of the Mouse PAS Domain Serine/Threonine Kinase PASKIN Mol. Cell. Biol., October 1, 2003; 23(19): 6780 - 6789. [Abstract] [Full Text] [PDF]