There is no fundamental distinction between signaling molecules that bind to cell-surface receptors and those that bind to intracellular receptors.

判断题Water has a high specific heat.

判断题The density of water is less than the density of ice.

判断题Both the GTP-bound a subunits and nucleotide-free b complexes, but not GDP-bound, fully assembled G proteins, activate other molecules downstream of G-protein-linked receptors.

填空题是细胞外基质的受体蛋白。在结构上，它们是异二聚体，。这种跨膜蛋白的细胞外部分有一个球形的头部，可与细胞外基质蛋白结合，而细胞质结构域则可与 相结合。

填空题编码载脂蛋白B的基因在肠组织中转录成mRNA后,第2153位的C被 形成U,使CAA密码转变成终止密码UAA, 使翻译提前终止。