Expression of a nonmyristylated variant of the catalytic subunit of protein kinase A during male germ-cell development
Expression of a nonmyristylated variant of the catalytic subunit of protein kinase A during male germ-cell development
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DOI：
10.1073/pnas.97.12.6433
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发表时间：
2000-06-06
影响因子：
11.1
通讯作者：
McKnight, GS
中科院分区：
文献类型：
--
作者：
Desseyn, JL;Burton, KA;McKnight, GS
蛋白激酶A的催化亚基在所有小鼠组织中都是从两个不同的基因转录而来的，这两个基因编码Cα和Cβ亚型。存在Cβ基因的替代启动子，这些启动子以组织特有的方式使用，并导致其氨基末端序列不同的变体。我们已经确定了存在于Cα基因第一内含子中的另一种启动子，该启动子在雄性生殖细胞中具有转录活性。此启动子的转录与粗线期精母细胞的出现相一致，并导致Cα蛋白(Cα2)含有与Cα1的14个氨基酸末端不同的7个氨基酸的氨基末端。Cα2蛋白不含存在于COIL上的肉豆蔻酸化信号，而在SDS/PACE凝胶上以较低的相对分子质量迁移。通过Western blotting，我们估计成熟精子中存在的Cα蛋白大部分或全部是Cα2。Cα2的氨基末端序列与先前报道的绵羊精子C相似[San Agustin，J.T.，Leszyk，J.D.，Nuway sir，L.M.&Witman，G.B.(1998)J.Biol]。化学。273,24874-24883]，我们通过cDNA克隆表明，人类精子也表达高度相关的Cα2同源物。Cα2亚基与RIIα或RIα形成全酶，并在相同浓度的环核苷酸下激活。由于蛋白激酶A被认为在精子运动和获能过程中起着关键作用，非肉豆蔻化Cα2的独特生化特性可能对男性的生育能力至关重要。
The catalytic subunits of protein kinase A are transcribed in all mouse tissues from two distinct genes that code for the C alpha and C beta isoforms. Alternative promoters exist for the C beta gene that are used in a tissue-specific fashion and give rise to variants that differ in their amino-terminal sequences. We have characterized an alternative promoter that is present in the first intron of the C alpha gene and is transcriptionally active in male germ cells. Transcription from this promoter is coincident with the appearance of pachytene spermatocytes and leads to a C alpha protein (C alpha 2) that contains a distinctive 7 amino acid amino-terminus differing from the 14 amino acid amino-terminus of C alpha 1. The C alpha 2 protein does not contain the myristylation signal present on coil and migrates at a lower molecular weight on SDS/PACE gels. By Western blotting, we estimate that most or all of the C alpha protein present in mature sperm is C alpha 2. The amino-terminal sequence of C alpha 2 is similar to that of ovine sperm C as previously reported [San Agustin, J. T., Leszyk, J. D., Nuwaysir, L. M. & Witman, G. B. (1998) J. Biol. Chem. 273, 24874-24883], and we show by cDNA cloning that human sperm also express a highly related C alpha 2 homolog. The C alpha 2 subunit forms holoenzymes with either RII alpha or RI alpha, and both activate at the same concentration of cyclic nucleotide. Because protein kinase A is thought to play a pivotal role in sperm motility and capacitation, the distinctive biochemical properties of the unmyristylated C alpha 2 may be essential for fertility in the male.