Membrane Protein; allows ions or small molecules to cross a membrane to the side where they are less concentrated. Open or gated channels. Does not require energy.
Membrane Protein; Pump ions or molecules through membranes to the side where they are more concentrated. Require energy input, such as ATP.
Membrane Protein; Initiate change in a cell's activity by responding to an outside signal (ex. by binding to a signaling molecule)
Cell Adhesion Molecules
Membrane Protein; Help cells stick to one another and to extracellular matrix (complex mixture that supports and anchors cells)
Identify cells as self (belonging to one's own body or tissue)
Membrane Protein; Speed reactions without being altered by them