Reprod Biol Endocrin
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Reprod Biol Endocrin · Jul 2004
Association of sperm protein 17 with A-kinase anchoring protein 3 in flagella.
Sperm protein 17 (Sp17) is a three-domain protein that contains: 1) a highly conserved N-terminal domain that is 45% identical to the human type II alpha regulatory subunit (RII alpha) of protein kinase A (PKA); 2) a central sulphated carbohydrate-binding domain; and 3) a C-terminal Ca++/calmodulin (CaM) binding domain. Although Sp17 was originally discovered and characterized in spermatozoa, its mRNA has now been found in a variety of normal mouse and human tissues. However, Sp17 protein is found predominantly in spermatozoa, cilia and human neoplastic cell lines. This study demonstrates that Sp17 from spermatozoa binds A-kinase anchoring protein 3 (AKAP3), confirming the functionality of the N-terminal domain. ⋯ As predicted by its N-terminal domain that is 45% identical to the human RIIalpha of PKA, Sp17 from spermatozoa binds the RII binding domain of AKAP3 along the length of the flagella.