Crystal structure at 2.4 angstroms resolution of the complex of transducin betagamma and its regulator, phosducin.
Crystal structure at 2.4 angstroms resolution of the complex of transducin betagamma and its regulator, phosducin.
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作者：
R. Gaudet;A. Bohm;P. Sigler
调节Gtbetagamma活性的转导蛋白β-amma亚基与硫代脱氢蛋白络合，其晶体结构的分辨率已达到2.4埃。Phosducin有两个结构域包裹在Gtbetagamma周围，形成一个广泛的界面。N-末端结构域在“顶部”的Gtbeta表面结合环，与Gtalpha结合表面重叠，解释了光导蛋白如何阻止Gtbetagamma与Gtalpha的相互作用。C-末端结构域显示出与硫氧还蛋白的结构同源性，并以一种可能破坏Gtbetagamma相对于膜和受体的正常取向的方式结合Gtbeta第七和第一叶片的外层。Phosducin的Ser-73在被磷酸化时抑制了Phosducin的功能，它从Gtbetagamma指向一个大的灵活的环。因此，磷酸化不太可能直接影响界面，而是通过诱导构象变化间接影响界面。
The crystal structure of transducin's betagamma subunits complexed with phosducin, which regulates Gtbetagamma activity, has been solved to 2.4 angstroms resolution. Phosducin has two domains that wrap around Gtbetagamma to form an extensive interface. The N-terminal domain binds loops on the "top" Gtbeta surface, overlapping the Gtalpha binding surface, explaining how phosducin blocks Gtbetagamma's interaction with Gtalpha. The C-terminal domain shows structural homology to thioredoxin and binds the outer strands of Gtbeta's seventh and first blades in a manner likely to disrupt Gtbetagamma's normal orientation relative to the membrane and receptor. Phosducin's Ser-73, which when phosphorylated inhibits phosducin's function, points away from Gtbetagamma, toward a large flexible loop. Thus phosphorylation is not likely to affect the interface directly, but rather indirectly through an induced conformational change.