Santa Cruz Biotechnology offers an expansive library of transfected lysates that overexpress membrane receptors. Membrane receptors are integral membrane proteins that usually reside and function within the lipid bilayer plasma membrane of a cell, but may also localize to the membranes of some subcellular compartments and organelles. The binding of a signaling molecule (or a pair of signaling molecules) to one side of the membrane causes membrane receptors to initiate a response on the other side, thus playing an important role in cellular communications and signal transduction. The extracellular domain is the part of the receptor that sticks out from the membrane and interacts with signals outside the cell. The transmembrane domain is typically composed of alpha helices and may contain a ligand binding pocket. The intracellular, or cytoplasmic, domain of the membrane receptor interacts with the interior of the cell to relay the intended signal. Transfected lysates that express membrane receptors offer a reliable means to evaluate antibody quality and serve as excellent positive controls for experiments involving antibodies.