膜蛋白的功能 Transport (a)A protein that spans the membrane may provide a hydrophillc channel across the membrane that is selective for a particular solute.(b)Some transport proteins hydrolyze ATP as an energy source to actively pump substances across the membrane. Signal transduction A membrane protein may have a binding site with a specific shape that fits the shape of a chemical messenger,such as a hormone.The external messenger(signal)may cause a conformational change in the protein that relays the message to the inslde of the cell. Adhesion Some ghycoproteins attach to the cytoskeleton and extracellular matrix. Cell-cell recognition Some glycoproteins(proteins with short chains of sugars)serve as identification tags that are specifically recognized by other cells. 膜蛋白的功能