Wagner T, Oppi C, Tocchini Valentini G P
EniChem SpA. Istituto Guido Donegani, Monterotondol Rome, Italy.
FEBS Lett. 1995 May 22;365(1):13-7. doi: 10.1016/0014-5793(95)00435-c.
The effect of peptides homologous to segments of a G protein-coupled receptor on the GTPase activity of recombinant Go alpha (rGo alpha) and Gs alpha (rGs alpha) has been tested. These peptides contain overlapping sequences spanning from amino acid 212 of the putative fifth transmembrane domain to amino acid 229 of the third cytoplasmic loop of the alpha 2 adrenergic receptor. Interestingly, two peptides (comprising residues 212-227 and 214-227) strongly inhibit the basal GTPase activity of both rGo alpha and rGs alpha. Instead, a C-terminally extended peptide (residues 216-229) stimulates rGo alpha but slightly inhibits rGs alpha. Circular dichroism spectroscopy of the peptides reveals that an a helical structure is more easily inducible in the inhibitory ones. These findings constitute an example of peptides representing cytoplasmic receptor sequences that differentially modulate the GTPase activity of recombinant G protein alpha-subunits.
已测试了与G蛋白偶联受体片段同源的肽对重组Goα（rGoα）和Gsα（rGsα）的GTP酶活性的影响。这些肽包含从假定的第五跨膜结构域的氨基酸212到α2肾上腺素能受体第三细胞质环的氨基酸229的重叠序列。有趣的是，两种肽（包含残基212 - 227和214 - 227）强烈抑制rGoα和rGsα的基础GTP酶活性。相反，C末端延伸的肽（残基216 - 229）刺激rGoα，但轻微抑制rGsα。肽的圆二色光谱显示，抑制性肽中更容易诱导出α螺旋结构。这些发现构成了代表细胞质受体序列的肽对重组G蛋白α亚基的GTP酶活性进行差异调节的一个例子。
