Pasqualone D, Huffaker T C
Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853.
J Cell Biol. 1994 Dec;127(6 Pt 2):1973-84. doi: 10.1083/jcb.127.6.1973.
We have isolated a cold-sensitive allele of TUB2, the sole gene encoding beta-tubulin in S. cerevisiae, that confers a specific defect in spindle microtubule function. At 14 degrees C, tub2-406 cells lack a normal bipolar spindle but do assemble functional cytoplasmic microtubules. In an attempt to identify proteins that are important for spindle assembly, we screened for suppressors of the cold-sensitivity of tub2-406 and obtained four alleles of a novel gene, STU1. Genetic interactions between stu1 alleles and alleles of TUB1 and TUB2 suggest that Stu1p specifically interacts with microtubules. STU1 is essential for growth and disruption of STU1 causes defects in spindle assembly that are similar to those produced by the tub2-406 mutation. The nucleotide sequence of the STU1 gene predicts a protein product of 174 kD with no significant similarity to known proteins. An epitope-tagged Stulp colocalizes with microtubules in the mitotic spindle of yeast. These results demonstrate that Stulp is an essential component of the yeast mitotic spindle.
我们分离出了TUB2的一个冷敏感等位基因，TUB2是酿酒酵母中唯一编码β-微管蛋白的基因，该等位基因在纺锤体微管功能上表现出特定缺陷。在14摄氏度时，tub2 - 406细胞缺乏正常的双极纺锤体，但能组装功能性的细胞质微管。为了鉴定对纺锤体组装重要的蛋白质，我们筛选了tub2 - 406冷敏感性的抑制子，并获得了一个新基因STU1的四个等位基因。stu1等位基因与TUB1和TUB2等位基因之间的遗传相互作用表明，Stu1p特异性地与微管相互作用。STU1对生长至关重要，STU1的破坏会导致纺锤体组装缺陷，这与tub2 - 406突变产生的缺陷相似。STU1基因的核苷酸序列预测其蛋白质产物为174 kD，与已知蛋白质无明显相似性。一个带有表位标签的Stulp与酵母有丝分裂纺锤体中的微管共定位。这些结果表明，Stulp是酵母有丝分裂纺锤体的一个重要组成部分。
