Teo M, Tan L, Lim L, Manser E
Glaxo-IMCB Group, Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609, Japan.
J Biol Chem. 2001 May 25;276(21):18392-8. doi: 10.1074/jbc.M008795200. Epub 2001 Feb 27.
One target for the small GTPase Cdc42 is the nonreceptor tyrosine kinase activated Cdc42-associated kinase (ACK), which binds selectively to Cdc42.GTP. We report that ACK1 can associate directly with the heavy chain of clathrin. A central region in ACK1 containing a conserved motif behaves as a clathrin adaptor and competes with beta-arrestin for a common binding site on the clathrin N-terminal head domain. Overexpressed ACK1 perturbs clathrin distribution, an activity dependent on the presence of C-terminal "adaptor" sequences that are also present in the related nonkinase gene 33. ACK1 interacts with the adaptor Nck via SH3 interactions but does not form a trimeric complex with p21-activated serine/threonine kinase, which also binds Nck. Stable low level expression of green fluorescent protein-ACK1 in NIH 3T3 cells has been used to localize ACK1 to clathrin-containing vesicles. The co-localization of ACK1 in vivo with clathrin and AP-2 indicates that it participates in trafficking, underlying an ability to increase receptor-mediated transferrin uptake.
小GTP酶Cdc42的一个作用靶点是由非受体酪氨酸激酶激活的Cdc42相关激酶（ACK），它能选择性地与Cdc42.GTP结合。我们发现ACK1可直接与网格蛋白重链结合。ACK1中包含一个保守基序的中央区域发挥着网格蛋白衔接蛋白的作用，并与β抑制蛋白竞争网格蛋白N端头部结构域上的一个共同结合位点。过表达的ACK1会扰乱网格蛋白的分布，这种活性依赖于相关非激酶基因33中也存在的C端“衔接蛋白”序列的存在。ACK1通过SH3相互作用与衔接蛋白Nck相互作用，但不与也结合Nck的p21激活的丝氨酸/苏氨酸激酶形成三聚体复合物。在NIH 3T3细胞中稳定低水平表达绿色荧光蛋白-ACK1已被用于将ACK1定位于含网格蛋白的小泡。ACK1在体内与网格蛋白和AP-2的共定位表明它参与了转运过程，这是其增强受体介导的转铁蛋白摄取能力的基础。
