Brown Rebecca L, August Shelley L, Williams Carmen J, Moss Stuart B
Center for Research on Reproduction and Women's Health, Department of Obstetrics and Gynecology, University of Pennsylvania, Rm. 1312 BRB II/III, 421 Curie Blvd., Philadelphia, PA 19104-6142, USA.
Biochem Biophys Res Commun. 2003 Jun 27;306(2):394-401. doi: 10.1016/s0006-291x(03)00982-3.
Spatial regulation of protein kinase A (PKA) is accomplished by its sequestration via A-kinase anchor proteins (AKAPs). PKA activity is critical for mammalian oocyte development, suggesting that PKA must be appropriately positioned in these large cells. A screen for AKAPs in oocytes identified AKAP7gamma, an AKAP originally found in pancreas. Yeast two-hybrid analysis and co-immunoprecipitation studies showed that AKAP7gamma bound the type I PKA regulatory subunit (RI) and that the RI-binding domain overlapped the previously identified type II PKA regulatory subunit (RII) binding domain. Overexpressed AKAP7gamma localized to the nuclei of HEK 293 cells via a nuclear localization signal. In addition, endogenous AKAP7gamma protein was found in both the nucleus and cytoplasm of oocytes. This work identifies AKAP7gamma as the first nuclear AKAP to bind RI and suggests that AKAP7gamma may be responsible for positioning PKA via RI and/or RII to regulate PKA-mediated gene transcription in both somatic cells and oocytes.
蛋白激酶A（PKA）的空间调控是通过其与A激酶锚定蛋白（AKAPs）结合来实现的。PKA活性对哺乳动物卵母细胞发育至关重要，这表明PKA必须在这些大细胞中恰当定位。对卵母细胞中AKAPs的筛选鉴定出了AKAP7γ，一种最初在胰腺中发现的AKAP。酵母双杂交分析和免疫共沉淀研究表明，AKAP7γ与I型PKA调节亚基（RI）结合，且RI结合域与先前鉴定的II型PKA调节亚基（RII）结合域重叠。过表达的AKAP7γ通过一个核定位信号定位于HEK 293细胞的细胞核。此外，在卵母细胞的细胞核和细胞质中均发现了内源性AKAP7γ蛋白。这项研究将AKAP7γ鉴定为首个与RI结合的核AKAP，并表明AKAP7γ可能负责通过RI和/或RII定位PKA，以调控体细胞和卵母细胞中PKA介导的基因转录。
