Smith L, Stull J T
Department of Physiology, The University of Texas Southwestern Medical Center at Dallas, 75390-9040, USA.
FEBS Lett. 2000 Sep 1;480(2-3):298-300. doi: 10.1016/s0014-5793(00)01931-1.
Smooth muscle myosin light chain kinase (MLCK) plays important roles in contractile-motile processes of a variety of cells. Three DFRxxL motifs at the kinase N-terminus (residues 2-63) are critical for high-affinity binding to actin-containing filaments [Smith et al. (1999) J. Biol. Chem. 274, 29433-29438]. A GST fusion protein containing residues 1-75 of MLCK (GST75-MLCK) bound maximally to both smooth muscle myofilaments and F-actin at 0.28 and 0.31 mol GST75-MLCK/mol actin with respective K(D) values of 0.1 microM and 0.8 microM. High-affinity binding of MLCK to actin-containing filaments may be due to each DFRxxL motif binding to one actin monomer in filaments.
平滑肌肌球蛋白轻链激酶（MLCK）在多种细胞的收缩运动过程中发挥着重要作用。激酶N端（第2 - 63位氨基酸残基）的三个DFRxxL基序对于与含肌动蛋白的细丝的高亲和力结合至关重要[史密斯等人（1999年）《生物化学杂志》274, 29433 - 29438]。一种包含MLCK第1 - 75位氨基酸残基的GST融合蛋白（GST75 - MLCK），在0.28和0.31摩尔GST75 - MLCK/摩尔肌动蛋白时分别与平滑肌肌丝和F - 肌动蛋白达到最大结合，其解离常数（K(D)）值分别为0.1微摩尔和0.8微摩尔。MLCK与含肌动蛋白细丝的高亲和力结合可能是由于每个DFRxxL基序与细丝中的一个肌动蛋白单体结合。
