title: Characterization of S-AKAP84, a novel developmentally regulated A kinase anchor protein of male germ cells.
abstract: In mammalian spermatozoa, most of the type II alpha isoform of cAMP-dependent protein kinase (PKAII alpha) is anchored at the cytoplasmic surface of a specialized array of mitochondria in the flagellar cytoskeleton. This places the catalytic subunits of PKAII alpha in proximity with potential target substrates in the cytoskeleton. The mechanism by which PKAII alpha is anchored at the outer surface of germ cell mitochondria has not been elucidated. We now report the cloning of a cDNA that encodes a novel, germ cell A kinase anchor protein (AKAP) designated S-AKAP84. S-AKAP84 comprises 593 amino acids and contains a centrally located domain that avidly binds regulatory subunits (RII alpha and RII beta) of PKAII alpha and PKAII beta. The 3.2-kilobase S-AKAP84 mRNA and the cognate S-AKAP84 RII binding protein are expressed principally in the male germ cell lineage. Expression of S-AKAP84 is tightly regulated during development. The protein accumulates as spermatids undergo nuclear condensation and tail elongation. The timing of S-AKAP84 expression is correlated with the de novo accumulation of RII alpha and RII beta subunits and the migration of mitochondria from the cytoplasm (round spermatids) to the cytoskeleton (midpiece in elongating spermatids). Residues 1-30 at the NH2 terminus of S-AKAP84 constitute a putative signal/anchor sequence that may target the protein to the outer mitochondrial membrane. Immunofluorescence analysis demonstrated that S-AKAP84 is co-localized with mitochondria in the flagellum.
mesh_terms: D054758:A Kinase Anchor Proteins; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D054754:Cyclic AMP-Dependent Protein Kinase RIIalpha Subunit; D054757:Cyclic AMP-Dependent Protein Kinase RIIbeta Subunit; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D017931:DNA Primers; D018076:DNA, Complementary; D015870:Gene Expression; D015723:Gene Library; D006801:Humans; D046911:Macromolecular Substances; D008297:Male; D008322:Mammals; D008565:Membrane Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D021382:Protein Sorting Signals; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D013087:Spermatids / Q000378:metabolism; D013090:Spermatocytes / Q000378:metabolism; D013094:Spermatozoa / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D013737:Testis / Q000378:metabolism*
chemical_list: D054758:A Kinase Anchor Proteins; C105137:AKAP1 protein, human; D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D054754:Cyclic AMP-Dependent Protein Kinase RIIalpha Subunit; D054757:Cyclic AMP-Dependent Protein Kinase RIIbeta Subunit; D017931:DNA Primers; D018076:DNA, Complementary; D046911:Macromolecular Substances; D008565:Membrane Proteins; C517819:PRKAR2A protein, human; C517837:PRKAR2B protein, human; D021382:Protein Sorting Signals; D012333:RNA, Messenger; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases