The cell membrane, also called the plasma membrane or plasmalemma, is a semipermeable lipid bilayer common to all living cells. It contains a variety of biological molecules, primarily proteins and lipids, which are involved in a vast array of cellular processes. It also serves as the attachment point for both the intracellular cytoskeleton and, if present, the cell wall.

The cell membrane surrounds the cytoplasm of a cell and physically separates the intracellular components from the extracellular environment, thereby serving a mechanical function similar to that of skin. This barrier is able to regulate what enters and exits the cell as it is selectively permeable - cells require a variety of substances to survive and the cell membrane serves as "gatekeeper" to what, and how much, enters and exits. The movement of substances across the membrane can be either passive, occurring without the input of cellular energy, or active, requiring the cell to expend energy moving it across the membrane.

5'-AMPase

• plasma membrane marker, and its activity is concentrated in the smooth muscle plasma membranes. PMID: 3040906

5'-Nucleotidase

• classical plasma membrane marker. PMID: 2826161
• a stable, quantitative plasma membrane marker in HeLa S3 cells. PMID: 45780

Acetylcholinesterase (AChE)

• presynaptic plasma membrane marker. PMID: 2398359
• plasma membrane marker enzyme. PMID: 8507304

Adenosine Triphosphatase (ATPase)

• Magnesium-dependent adenosine triphosphatase as a marker enzyme for the plasma membrane of human polymorphonuclear leukocytes. PMID: 14892
• yeast plasma membrane marker. PMID: 6129837

Alkaline Phosphatase

• Alkaline phosphatase distribution in the plasma membrane of uterine epithelial cells is markedly altered during early pregnancy in the rat. PMID: 8574218
• cytochemical activity for nonspecific AP is concentrated on the basolateral plasma membrane domain of normal retinal pigment epithelium (RPE) and the normal pattern of AP activity is lost initially and then reexpressed. PMID: 1748550

Alkaline Phosphodiesterase I

• classical plasma membrane marker. PMID: 2826161

Cadherin (pan)

• a core N-cadherin-catenin complex assembles in the endoplasmic reticulum or Golgi compartment and is transported to the plasma membrane where linkage to the actin cytoskeleton can be established. PMID: 12604612

CD27

• a transmembrane glycoprotein found exclusively on human T and B lymphocytes. It belongs to a recently identified receptor family, whose members are involved in cell differentiation and survival. PMID: 1311261
• belongs to a newly defined family of transmembrane R, including the nerve growth factor R, two distinct TNF R and CD40. Upon Ag-specific T cell stimulation, membrane expression of CD27 is regulated at the RNA level through the joint action of distinct TCR/CD3-associated signaling pathways. PMID: 1707907

CD40

• a membrane glycoprotein expressed on normal and neoplastic B lymphocytes. PMID: 9056740
• CD40 receptors on human monocyte-derived DCs associate with sphingolipid- and cholesterol-rich plasma membrane microdomains, termed membrane rafts. PMID: 10880443

CD95-ligand (CD95-L) (Fas-L)

• expressed on the plasma membrane of human activated, but not resting, Langerhans' cells. PMID: 14705811
• Keratinocytes constitutively express the CD95 ligand molecule on the plasma membrane: an in situ immunoelectron microscopy study on ultracryosections of normal human skin. PMID: 12100178

Concanavalin A

• Concanavalin A could be used unambiguously as an exogenous plasma membrane marker of intact protoplasts. PMID: 6129837

Cytochrome B

• can be measured by its light-induced absorbance change and may serve as a marker for the plant plasma membrane. PMID: 16662693

Ezrin 

• belongs to a family of plasma membrane-cytoskeleton linking, actin binding proteins (Ezrin-radixin-Moesin family) involved in signal transduction, growth control, cell-cell adhesion, and microvilli formation. PMID: 9853258

FADD

• the 62 kDa FadD enzyme is a substrate for the outer membrane protease OmpT in vitro, producing a 43 kDa C-terminal fragment and a 19 kDa N-terminal fragment. PMID: 11736662

FM1-43

• a membrane-impermeable lipid marker. PMID: 15710604

Gamma-Glutamyltransferase

• has been found to be entirely plasma membrane in location but has a different distribution pattern when compared with other plasma membrane markers. PMID: 7371635

Grb2

• Grb2 and BLNK cooperate to localize Vav into membrane rafts, thereby contributing to optimal activation of Vav in B cells. PMID: 12818159

HA 4 and CE 9

• the integral plasma membrane protein antigens, localized to the bile canalicular and sinusoidal/lateral domains, respectively, of the hepatocyte plasma membrane in rat liver tissue. PMID: 2984213

HLA class I antigen

• a plasma membrane marker. PMID: 2181625

LPM

• liver plasma membrane marker. PMID: 3623011

Leucine Aminopeptidase (LAP)/Leucine 2-Naphthylamidase

• a specific marker for the bile canalicular (BC) domain of the rat hepatocyte plasma membrane (PM). PMID: 6201493, PMID: 6371022
• a domain-specific marker for the hepatocyte plasma membrane. PMID: 6304108

PC-1

• Plasma cell membrane glycoprotein 1. PMID: 15209435

periodic NADH oxidase

• an enzyme marker for right side-out plasma membrane vesicles not requiring detergent disruptions of vesicles for measurement of activity. PMID: 10942307

PLAP (Human placental alkaline phosphatase)

• localized at the apical and basal plasma membrane of syncytiotrophoblasts and at the surface of cytotrophoblasts in term chorionic villi using immunoelectron microscopy. PMID: 11511684

Pma1

• a plasma membrane H(+)-ATPase whose activity at the cell surface is essential for cell viability. PMID: 11481477
• a very abundant polytopic membrane protein, and its localization and activity at the plasma membrane are essential for cell viability and growth. PMID: 16928681
• a plasma membrane H(+)-ATPase, is an essential and long-lived integral membrane protein. PMID: 12244215

PMCA (plasma membrane Ca2+ transport ATPase)

• Immunohistochemistry showed that PMCA immunoreactions were restricted to the osteoidal domain of the plasma membrane. PMID: 15542032

RLPM

• rabbit liver plasma membrane marker. PMID: 3623011

TNF-R1

• TNF-R1 is found on the cell surface but principally localizes to the trans-Golgi network, TRADD is concentrated in the cis- or medial-Golgi region, but separates from the Golgi during cell fractionation. PMID: 9916731

Other Plasma Membrane Markers 

• cytoplasmic and plasma membrane marker enzymes: lactate dehydrogenase (LDH) and acetylcholinesterase (AChE). PMID: 8507304
• K(+)-stimulated Mg(2+)-dependent ATPase and glucan synthetase II are two tentative markers for the plant plasma membrane. PMID: 16662693
• Silicotungstic acid, an indicative stain for the plasma membrane, stained the vesicles recovered from the upper phase, but failed to stain the membranes partitioning in the lower phase or at the interface. PMID: 16662693
• (poly) Phosphoinositide phosphorylation is a marker for plasma membrane in Friend erythroleukaemic cells. PMID: 6959824
• Trypan Blue as a marker of plasma membrane permeability in alloxan-treated mouse islet cells. PMID: 226577
• Isolation and characterization of the plasma membrane of L-1210 cells. Iodination as a marker for the plasma membrane. PMID: 168926
• Colloidal lanthanum as a marker for impaired plasma membrane permeability in ischemic dog myocardium. PMID: 1146960
• Properties of a synthetic plasma membrane marker: fluorescent-mercury-dextran. PMID: 4272697
• A fluorescent chemical marker for the liver cell plasma membrane. PMID: 6048244
• Cytochemical localization of plasma membrane enzyme markers during interiorization of tachyzoites of Toxoplasma gondii by macrophages. PMID: 2542539
• Canine neutrophil plasma membrane markers. PMID: 2983765