酵母交配过程的极性生长及其调控机制

酿酒酵母单倍体细胞能够与相反交配型的单倍体细胞发生交配。交配时酿酒酵母放弃原有出芽位点,根据信息素的浓度梯度,重新选择生长位点,向相反交配型细胞伸出突起进行极性生长。交配因子受体指导选择交配突起的位点,通过G蛋白激活Ste20p,将信号经由Ste11p、Ste7p和Fus3p组成的MAPK模块传递到Far1p和Ste12p等因子,调控相关基因的转录,抑制原有的出芽位点,选择新的生长位点,并使细胞周期停止在G1期,G蛋白与Cdc24p、Cdc42p和Bem1p等蛋白作用,聚集在细胞,使得肌协蛋白细胞骨架在交配突起处聚集,呈极性化分布,使细胞发生极性生长。

Polarized growth during mating in Saccharomyces cerevisiae

Haploid yeast cells are able to mate with partner of different mating type. Responding to the gradient of pheromone, cells discard the previous axial landmark and grow toward the partner. Pheromone receptor may direct the selection of mating project. The G protein complex activates downstream protein Ste20p, and it in turn stimulate the Stellp-Ste7p-Fus3p MAPK cascade. Far1p, Stel2p are phosphorylated by Fus3p then mediate choose of projection site, cell cycle arrest in G1, regulation of expression of genes involved in mating response. The actin polarization in mating project is also induced by G protein complex through Cdc24p, Cdc42p, Bem1p, etc. Polarized growth is directed toward the site.