Jenness D D, Burkholder A C, Hartwell L H
Cell. 1983 Dec;35(2 Pt 1):521-9. doi: 10.1016/0092-8674(83)90186-1.
The division cycle of yeast a cells is inhibited by alpha-factor. Haploid a cells were found to bind 35S-labeled alpha-factor, whereas haploid alpha cells and diploid a/alpha cells showed little binding. The association of alpha-factor with a cells was reversible upon dilution. Unlabeled alpha-factor competed for binding of 35S-alpha-factor; the concentration dependence for competition indicated 9 X 10(5) binding sites per cell with a dissociation constant (KD) of 3 X 10(-7) M. The rates of association (kon = 3 X 10(3) M-1 sec-1) and dissociation (koff = 9 X 10(-4) sec-1) were consistent with the equilibrium constant. The alpha-factor binding activity associated with five temperature-sensitive ste2 mutants was thermolabile, suggesting that the STE2 gene encodes the receptor for alpha-factor. In contrast, the binding activity of other temperature-sensitive mutants (ste4, ste5, ste7, ste11, and ste12) showed no thermolability.
酵母a细胞的分裂周期受到α因子的抑制。发现单倍体a细胞能结合35S标记的α因子，而单倍体α细胞和二倍体a/α细胞几乎不结合。稀释后，α因子与a细胞的结合是可逆的。未标记的α因子能竞争35S-α因子的结合；竞争的浓度依赖性表明每个细胞有9×10⁵个结合位点，解离常数（KD）为3×10⁻⁷M。结合速率（kon = 3×10³M⁻¹秒⁻¹）和解离速率（koff = 9×10⁻⁴秒⁻¹）与平衡常数一致。与五个温度敏感型ste2突变体相关的α因子结合活性是热不稳定的，这表明STE2基因编码α因子的受体。相比之下，其他温度敏感型突变体（ste4、ste5、ste7、ste11和ste12）的结合活性没有热不稳定性。
