Kelly G M, Zelus B D, Moon R T
Department of Pharmacology, University of Washington School of Medicine, Seattle 98195.
J Biol Chem. 1991 Jul 5;266(19):12469-73.
Xenopus membrane skeleton protein 4.1 is expressed constitutively during embryonic development and accumulates to high levels within the retina during normal morphogenesis. There exists a high degree of amino acid identity between Xenopus protein 4.1 and human protein 4.1, suggesting that the mechanisms known to modulate the function(s) of human protein 4.1 may also serve to regulate Xenopus protein 4.1. Calmodulin (CaM) is one regulatory protein known to affect membrane-cytoskeletal interactions. An in vitro binding assay was used to test the ability of Xenopus protein 4.1 to bind CaM. Two independent approaches, involving protein 4.1 synthesized in vitro from synthetic RNA or a partial length protein 4.1 fusion protein expressed in Escherichia coli, demonstrate calcium-dependent, CaM binding. Both approaches demonstrate that the CaM-binding site is within the amino-terminal region of Xenopus protein 4.1. Results of this calmodulin binding activity suggest a possible regulatory mechanism by which calcium and calmodulin may affect the function of protein 4.1 during development.
非洲爪蟾膜骨架蛋白4.1在胚胎发育过程中持续表达，并在正常形态发生过程中在视网膜内积累至高水平。非洲爪蟾蛋白4.1与人类蛋白4.1之间存在高度的氨基酸同一性，这表明已知调节人类蛋白4.1功能的机制也可能用于调节非洲爪蟾蛋白4.1。钙调蛋白（CaM）是一种已知会影响膜 - 细胞骨架相互作用的调节蛋白。体外结合试验用于测试非洲爪蟾蛋白4.1结合CaM的能力。两种独立的方法，一种涉及从合成RNA体外合成的蛋白4.1，另一种涉及在大肠杆菌中表达的部分长度蛋白4.1融合蛋白，均证明了钙依赖性的CaM结合。两种方法均表明CaM结合位点在非洲爪蟾蛋白4.1的氨基末端区域内。这种钙调蛋白结合活性的结果提示了一种可能的调节机制，通过该机制钙和钙调蛋白可能在发育过程中影响蛋白4.1的功能。
