Barroso M R, Bernd K K, DeWitt N D, Chang A, Mills K, Sztul E S
Department of Cell Biology, University of Alabama Medical Center, Birmingham, Alabama 35294, USA.
J Biol Chem. 1996 Apr 26;271(17):10183-7. doi: 10.1074/jbc.271.17.10183.
We have identified a novel protein, p22, required for "constitutive" exocytic membrane traffic. p22 belongs to the EF-hand superfamily of Ca2+-binding proteins and shows extensive similarity to the regulatory subunit of protein phosphatase 2B, calcineurin B. p22 is a cytosolic N-myristoylated protein that undergoes conformational changes upon binding of Ca2+. Antibodies against a p22 peptide block the targeting/fusion of transcytotic vesicles with the apical plasma membrane, but recombinant wild-type p22 overcomes that inhibition. Nonmyristoylated p22, or p22 incapable of undergoing Ca2+-induced conformational changes, cannot reverse the antibody-mediated inhibition. The data suggest that p22 may act by transducing cellular Ca2+ signals to downstream effectors. p22 is ubiquitously expressed, and we propose that its function is required for membrane trafficking events common to many cells.
我们鉴定出一种新型蛋白质p22，它是“组成型”胞吐膜运输所必需的。p22属于Ca2+结合蛋白的EF手超家族，与蛋白磷酸酶2B（钙调神经磷酸酶B）的调节亚基具有广泛的相似性。p22是一种胞质N-肉豆蔻酰化蛋白，在结合Ca2+后会发生构象变化。针对p22肽的抗体可阻断转胞吞小泡与顶端质膜的靶向/融合，但重组野生型p22可克服这种抑制作用。非肉豆蔻酰化的p22或不能发生Ca2+诱导的构象变化的p22无法逆转抗体介导的抑制作用。数据表明，p22可能通过将细胞Ca2+信号转导至下游效应器来发挥作用。p22在全身广泛表达，我们认为其功能是许多细胞共有的膜运输事件所必需的。
