Membrane Proteins
receptor proteins
Function as binding sites for chemical signals in the extracellular fluid; binding of chemical signals to receptors triggers cellular responses
carrier proteins
move ions or molecules across the plasma membrane; binding of specific chemicals to carrier proteins causes changes in the shape of the carrier proteins; the carrier proteins then move the specific chemical across the plasma membrane
Enzymes
Catalysts for chemical reactions in living things
ATP-powered pumps
Move specific ions or molecules across the membrane; require ATP molecules to function
Marker molecules
allow cells to identify other cells or other molecules
atachment proteins
anchor cells to other cells (catherins) or to extracellular maolecules (integrins)
channel proteins
form passage ways throufh the plasma membrane, allowing specific ions or molecules to enter or exit the cell; may be leake or gated