Transport (a) A protein that spans the membrane may provide a hydrophilic channel across the membrane that is selective for a oo particular solute.(b)Some transport proteins hydrolyze ATP as an energy source to actively pump substances across the membrane la) b) Functions of 点AT Signal transduction A membrane protein may have a binding membrane site with a specific shape that fits the shape of a chemical co messenger, such as a hormone. The external messenger(signal)may proteins cause a conformational change in the protein that relays the boo message to the inside of the cell Adhesion Some glycoproteins 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 I recognized by other cellsFunctions of membrane proteins Adhesion Some glycoproteins attach to the cytoskeleton and extracellular matrix