Schmidt S, Sohrmann M, Hofmann K, Woollard A, Simanis V
Cell Cycle Control Laboratory, Swiss Institute for Experimental Cancer Research (ISREC), Epalinges.
Genes Dev. 1997 Jun 15;11(12):1519-34. doi: 10.1101/gad.11.12.1519.
The spg1 gene (septum-promoting GTPase) was cloned as a multicopy suppressor of a dominant-negative mutant of the Cdc7p kinase. It encodes a small GTPase of the Ras superfamily. spg1 is an essential gene. Null or heat-sensitive alleles do not make a division septum, but growth, S-phase, and mitosis continue in the absence of cell division, producing elongated, multinucleate cells. Increased expression of Spg1p induces septum formation in G2, S-phase, and pre-Start G1-arrested cells. This requires the activity of Cdc7p kinase, but not p34(cdc2). Increased expression of Cdc7p bypasses the requirement for Spg1p. Spg1p and Cdc7p can be coimmunoprecipitated from cell extracts, and interact in the two-hybrid system. These data indicate that Spg1p is a key element in controlling the onset of septum formation in Schizosaccharomyces pombe, and that it acts through the Cdc7p kinase.
spg1基因（隔膜促进GTP酶）作为Cdc7p激酶显性负突变体的多拷贝抑制子被克隆。它编码Ras超家族的一个小GTP酶。spg1是一个必需基因。无效或热敏感等位基因不会形成分裂隔膜，但在没有细胞分裂的情况下生长、S期和有丝分裂仍会继续，产生细长的多核细胞。Spg1p表达增加会在G2期、S期和处于起始前G1期阻滞的细胞中诱导隔膜形成。这需要Cdc7p激酶的活性，但不需要p34(cdc2)。Cdc7p表达增加可绕过对Spg1p的需求。Spg1p和Cdc7p可从细胞提取物中共免疫沉淀，并在双杂交系统中相互作用。这些数据表明Spg1p是控制粟酒裂殖酵母隔膜形成起始的关键元件，并且它通过Cdc7p激酶发挥作用。
