CIL:35897, Saccharomyces cerevisiae. In Cell Image Library

A time lapse experiment of Saccharomyces cerevisiae expressing GFP tagged Lte1.

LTE1 is essential for termination of M phase at low temperatures, along with TEM1, and CDC15, all part of the mitotic exit network which is an elaborate signaling system comprising at least eight essential genes: CDC5, CDC14, CDC15, DBF2, DBF20, LTE1, MOB1, and TEM1. LTE1 was originally discovered as a locus essential for growth at 8 C, and was named for this trait as Low Temperature Essential 1. It was later inferred from sequence similarities that LTE1 must code for a guanine nucleotide exchange factor. Genetic evidence suggests that Lte1p activates the GTPase Tem1p which activates the protein kinase Cdc15p. Cdc15p then relieves the inhibition of the protein phosphatase Cdc14p by Net1p, thereby allowing exit from mitosis. In a normal cell cycle, Bub2p bound to Tem1p restrains mitotic exit until the daughter-bound centrosome (with which both Bub2p and Tem1p preferentially associate) comes into contact with Lte1p in the bud, effectively coupling mitotic exit with nuclear segregation. Some evidence suggests that the spatial separation of Tem1p and Lte1p is a key mechanism for controlling the timing of mitotic exit.

These phase,gfp images are part of an image group that ranges from CIL:35880-35899. Note that there are additional groups showing time series of other cell cycle regulation proteins by the same authors in the Library.

本数据集为表达绿色荧光蛋白（GFP）标记Lte1的酿酒酵母（Saccharomyces cerevisiae）延时拍摄实验。

LTE1与TEM1、CDC15均为有丝分裂退出网络（mitotic exit network）的组成部分，该网络是一套包含至少8个必需基因的复杂信号系统，涉及CDC5、CDC14、CDC15、DBF2、DBF20、LTE1、MOB1及TEM1。LTE1在低温条件下对M期（M phase）的终止至关重要。该基因最初作为8℃下生长必需的基因座被发现，并因此被命名为低温必需因子1（Low Temperature Essential 1，即LTE1）。后续通过序列相似性分析推断，LTE1编码一种鸟苷酸交换因子（guanine nucleotide exchange factor）。遗传学证据表明，Lte1p可激活GTP酶Tem1p，而Tem1p进而激活蛋白激酶Cdc15p；Cdc15p随后可解除Net1p对蛋白磷酸酶Cdc14p的抑制作用，最终使细胞退出有丝分裂。在正常细胞周期中，结合于Tem1p的Bub2p会抑制有丝分裂退出，直至与Bub2p和Tem1p优先结合的子代中心体与芽体中的Lte1p接触，从而将有丝分裂退出与核分离过程耦联。多项研究证据显示，Tem1p与Lte1p的空间分隔是调控有丝分裂退出时序的关键机制。

本部分相差显微镜成像与GFP荧光图像隶属于CIL:35880-35899图像组。需注意，该图库中另有同一作者团队拍摄的其他细胞周期调控蛋白的时间序列图像组。