Barroso M, Nelson D S, Sztul E
Department of Molecular Biology, Princeton University, NJ 08544.
Proc Natl Acad Sci U S A. 1995 Jan 17;92(2):527-31. doi: 10.1073/pnas.92.2.527.
Transcytosis-associated protein (TAP) is found on transytotic vesicles (TCVs) and is required for their fusion with the target membrane. We developed a cell-free assay capable of differentiating targeting/binding of TCVs to membrane from later fusion events. We found that TAP mediates stable association of TCVs with the target membrane. The sequence of rat liver TAP (959-amino acid open reading frame) encodes a protein that contains (i) an N-terminal region (amino acids 1-649), (ii) an internal region with several coiled-coil stretches (amino acids 650-930), and (iii) a C-terminal acidic region (amino acids 931-959). Comparisons between TAP and other sequences indicate that TAP is identical to p115, a protein involved in cis to medial Golgi transport, and homologous to Uso1p, a yeast protein involved in endoplasmic reticulum to Golgi transport. Our findings suggest that TAP/p115/Usop1 is a general factor acting within the secretory and endocytic pathways to bind transport vesicles prior to membrane fusion.
转胞吞作用相关蛋白（TAP）存在于转胞吞小泡（TCV）上，是其与靶膜融合所必需的。我们开发了一种无细胞检测方法，能够区分TCV与膜的靶向/结合以及随后的融合事件。我们发现TAP介导TCV与靶膜的稳定结合。大鼠肝脏TAP的序列（959个氨基酸的开放阅读框）编码一种蛋白质，该蛋白质包含：（i）一个N端区域（第1至649个氨基酸），（ii）一个带有几个卷曲螺旋结构域的内部区域（第650至930个氨基酸），以及（iii）一个C端酸性区域（第931至959个氨基酸）。TAP与其他序列的比较表明，TAP与参与顺式到中间高尔基体转运的蛋白p115相同，并且与参与内质网到高尔基体转运的酵母蛋白Uso1p同源。我们的研究结果表明，TAP/p115/Usop1是一种在分泌和内吞途径中起作用的通用因子，在膜融合之前结合运输小泡。
