Essentially, what they are is it's a protein that spans the membrane of a cell.

本质上来说，它是一个横跨细胞膜的蛋白质。

麻省理工公开课 - 化学原理课程节选

For now, just picture it in this simple way as a molecule, usually a protein, that's embedded in the cell membrane and many receptors have a part of them that is extracellular.

现在,我只把这种分子图示出来,受体通常是一种蛋白质,它们镶嵌在细胞膜上,很多受体还有部分结构露在细胞外

耶鲁公开课 - 生物医学工程探索课程节选

Now that's not the only thing in cell membranes, there are also proteins in cell membranes, and these proteins are special proteins that can exist within membranes like this, and they exist because these proteins also have different segments with different properties.

但细胞膜并不只由磷脂构成,细胞膜里还有蛋白质,而且这些蛋白质是一些,可以在细胞膜中存在的特殊的蛋白质,而这些蛋白质存在于细胞膜中,源于它们也有溶解性不同的片段

耶鲁公开课 - 生物医学工程探索课程节选