Cell cycle regulation of a lympho-hematopoietic specific Rap1GTPase-activating protein, Spa-1 in lymphocyres.

我们克隆了小鼠SPA-1基因（SPA-1）的人类同源物，其编码130 kDa（p130）的胞质蛋白，具有SH 3结合、Rap1GAP.PEST和亮氨酸拉链/卷曲螺旋结构域。在杆状病毒系统中表达的p130表现出特异性的针对Rap 1的GTP酶激活活性。在NIH 3 T3细胞中过表达一个截短的Spa-1cDNA明显干扰了G 0期阻滞的NIH 3 T3细胞在促有丝分裂刺激后进入细胞周期，表明该蛋白通过与Rap 1的相互作用参与细胞周期调控。基因组定位结果表明，小鼠Spa 1基因位于19号染色体的最着丝粒区，而人类Spa 1基因位于11q13.3的CCND 1/PRAD 1基因的着丝粒区附近。

We have cloned a human homologue of mouse Spa-1 gene (SPA-1) which encodes a 130 kDa (p130) cytoplasmic protein with SH3-binding, Rap1GAP.PEST and leucine zipper/coiled coil domains. p130 expressed in a Baculovirus system exhibits a specfic GTPase-activating activity against Rap1. Overexpression of a truncated Spa-1cDNA in NIH3T3 cells apparently disturbed the entry into the cell cycle in the G0-arrested NIH3T3 cells following mitogenic stimulation, suggesting that the protein is critically involved in the cell cycle regulation via the interaction with Rap1. Genomic mapping indicated that Spa-1 is located at the most centromeric region of chromosome 19 in mouse and at the centrimieric neighborhood of CCND1/PRAD1, a presumed BCL1 oncogene, at 11q13.3 in human.