Bajaj Anshika, Connelly Sara M, Gehret Austin U, Naider Fred, Dumont Mark E
Department of Biochemistry and Biophysics, P.O. Box 712, University of Rochester, School of Medicine and Dentistry, Rochester, NY 14642, USA.
Biochim Biophys Acta. 2007 Jun;1773(6):707-17. doi: 10.1016/j.bbamcr.2007.02.002. Epub 2007 Feb 17.
The yeast pheromone receptor, Ste2p, is a G protein coupled receptor that initiates cellular responses to alpha-mating pheromone, a 13 residue peptide that carries a net positive charge at physiological pH. We have examined the role of extracellular charged groups on the receptor in response to the pheromone. Substitutions of Asn or Ala for one extracellular residue, Asp275, affected both pheromone binding and signaling, suggesting that this position interacts directly with ligand. The other seven extracellular acidic residues could be individually replaced by polar residues with no detectable effects on receptor function. However, substitution of Ala for each of these seven residues resulted in impairment of signaling without affecting pheromone binding, implying that the polar nature of these residues promotes receptor activation. In contrast, substitution of Ala for each of the six positively charged residues at the extracellular surface of Ste2p did not affect signaling.
酵母信息素受体Ste2p是一种G蛋白偶联受体，它能启动细胞对α-交配信息素的反应，α-交配信息素是一种13个残基的肽，在生理pH值下带净正电荷。我们研究了受体上细胞外带电基团在对信息素反应中的作用。用天冬酰胺或丙氨酸取代一个细胞外残基天冬氨酸275，会影响信息素结合和信号传导，这表明该位置直接与配体相互作用。其他七个细胞外酸性残基可以分别被极性残基取代，而对受体功能没有可检测到的影响。然而，用丙氨酸取代这七个残基中的每一个都会导致信号传导受损，而不影响信息素结合，这意味着这些残基的极性性质促进了受体激活。相比之下，用丙氨酸取代Ste2p细胞外表面的六个带正电荷残基中的每一个并不影响信号传导。
