Cosgrove D J
Department of Biology, 208 Mueller Laboratory, Pennsylvania State University, Pennsylvania, 16802, USA.
Curr Opin Plant Biol. 2000 Feb;3(1):73-8. doi: 10.1016/s1369-5266(99)00039-4.
Expansins are extracellular proteins that loosen plant cell walls in novel ways. They are thought to function in cell enlargement, pollen tube invasion of the stigma (in grasses), wall disassembly during fruit ripening, abscission and other cell separation events. Expansins are encoded by two multigene families and each gene is often expressed in highly specific locations and cell types. Structural analysis indicates that one expansin region resembles the catalytic domain of family-45 endoglucanases but glucanase activity has not been detected. The genome projects have revealed numerous expansin-related sequences but their putative wall-loosening functions remain to be assessed.
扩展蛋白是一类细胞外蛋白，它们以新颖的方式使植物细胞壁松弛。人们认为它们在细胞扩张、花粉管侵入柱头（在禾本科植物中）、果实成熟过程中的细胞壁解体、脱落及其他细胞分离事件中发挥作用。扩展蛋白由两个多基因家族编码，每个基因通常在高度特异的位置和细胞类型中表达。结构分析表明，扩展蛋白的一个区域类似于45家族内切葡聚糖酶的催化结构域，但尚未检测到葡聚糖酶活性。基因组计划已揭示了许多与扩展蛋白相关的序列，但其假定的细胞壁松弛功能仍有待评估。
