Sjölin C, Stendahl O, Dahlgren C
Department of Medical Microbiology and Immunology, University of Göteborg, Sweden.
Biochem J. 1994 Jun 1;300 ( Pt 2)(Pt 2):325-30. doi: 10.1042/bj3000325.
The annexins are Ca(2+)-regulated, phospholipid-binding proteins which have been suggested to take part in cellular events such as exocytosis. The subcellular localization of annexins in human neutrophils was determined using monoclonal antibodies against annexins I, II, IV and VI and a polyclonal peptide antiserum against an annexin consensus sequence. Several annexins were translocated to the light membrane fraction enriched in plasma membranes and secretory vesicles. Annexins were associated also with the azurophil and specific granules. Whereas annexins I, IV and VI and one unidentified 35 kDa protein translocated to each of the isolated organelles, annexin II, a 66 kDa annexin IV-like protein, and a 38 kDa annexin I-like protein exhibited organelle-related differences in their association with membranes. The 38 kDa annexin associated only with specific granules and the secretory vesicles/plasma membrane but not with azurophil granules. Annexin II and the 66 kDa annexin IV-like protein associated with each of the neutrophil organelles, but the binding to specific granules and secretory vesicles/plasma membrane showed a Ca(2+)-dependency different from that of azurophil granules. This observation suggests that these proteins may contribute to the secretory process in neutrophils.
膜联蛋白是受Ca(2+)调节的磷脂结合蛋白，有人认为它们参与诸如胞吐作用等细胞活动。利用抗膜联蛋白I、II、IV和VI的单克隆抗体以及针对膜联蛋白共有序列的多克隆肽抗血清，确定了膜联蛋白在人中性粒细胞中的亚细胞定位。几种膜联蛋白转移到富含质膜和分泌小泡的轻膜组分中。膜联蛋白也与嗜天青颗粒和特异性颗粒相关。虽然膜联蛋白I、IV和VI以及一种未鉴定的35 kDa蛋白转移到每个分离的细胞器中，但膜联蛋白II（一种66 kDa的类似膜联蛋白IV的蛋白）和一种38 kDa的类似膜联蛋白I的蛋白在与膜的结合上表现出与细胞器相关的差异。38 kDa的膜联蛋白仅与特异性颗粒以及分泌小泡/质膜相关，而不与嗜天青颗粒相关。膜联蛋白II和66 kDa的类似膜联蛋白IV的蛋白与中性粒细胞的每个细胞器相关，但与特异性颗粒和分泌小泡/质膜的结合表现出与嗜天青颗粒不同的Ca(2+)依赖性。这一观察结果表明，这些蛋白可能有助于中性粒细胞的分泌过程。
