Conservation and function of a bovine sperm A-kinase anchor protein homologous to mouse AKAP82.
Protein kinase A regulates sperm motility through the cAMP-dependent phosphorylation of proteins. One mechanism to direct the activity of the kinase is to localize it near its protein substrates through the use of anchoring proteins. A-Kinase anchoring proteins (AKAPs) act by binding the type II regulatory subunit of protein kinase A and tethering it to a cellular organelle or cytoskeletal element. We showed previously that mAKAP82, the major protein of the fibrous sheath of the mouse sperm flagellum, is an AKAP. The available evidence indicates that protein kinase A is compartmentalized to the fibrous sheath by binding mAKAP82. To characterize AKAP82 in bovine sperm, a testicular cDNA library was constructed and used to isolate a clone encoding bAKAP82, the bovine homologue. Sequence analysis showed that the primary structure of bAKAP82 was highly conserved. In particular, the amino acid sequence corresponding to the region of mAKAP82 responsible for binding the regulatory subunit of protein kinase A was identical in the bull. Bovine AKAP82 was present in both epididymal and ejaculated sperm and was localized to the entire principal piece of the flagellum, the region in which the fibrous sheath is located. Finally, bAKAP82 bound the regulatory subunit of protein kinase A. These data support the idea that bAKAP82 functions as an anchoring protein for the subcellular localization of protein kinase A in the flagellum.
Center for Research on Reproduction and Women's Health, Department of Obstetrics and Gynecology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104, USA. smoss@mail.med.upenn.edu
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D054758:A Kinase Anchor Proteins; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry; D002417:Cattle; D054754:Cyclic AMP-Dependent Protein Kinase RIIalpha Subunit; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004822:Epididymis / Q000737:chemistry; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D029589:Seminal Plasma Proteins; D017386:Sequence Homology, Amino Acid; D013082:Sperm Tail / Q000737:chemistry* / Q000201:enzymology
D054758:A Kinase Anchor Proteins; D048868:Adaptor Proteins, Signal Transducing; C485611:Akap3 protein, mouse; D002352:Carrier Proteins; D054754:Cyclic AMP-Dependent Protein Kinase RIIalpha Subunit; C517821:Prkar2a protein, mouse; D011506:Proteins; D029589:Seminal Plasma Proteins; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases