ORGANELLE MARKERS - Plasma membrane - peripherial

FADD/MORT1

Fas-associating death domain containing protein (FADD)/MORT1 is a 23 kDa cytosolic protein, with an apparent molecular mass of 28 kDa on SDS PAGE, that serves as a signal transducer of Fasinduced ap. FADD contains a death domain homologous to that of Fas and interacts with the cytoplasmic death domain of Fas in order to initiate the apoptotic signalling cascade. Through its amino-terminal death effector domain (DED), FADD binds to cytosolic proteins such as TRADD, a cytosolic death domaincontaining protein that asssociates with the cytosolic portion of TNF receptor, or MACH/FLICE/caspase-8, a protease with sequence homology to ICE-CED-3 protease family, in order to transduce the death signal. The FADD-FLICE containing signalling complex is inhibited by a number of cytosolic factors such as the ICE/CED3 family inhibitor CrmA, which inhibits the protease activity of FLICE, and the short and long form of FLIP, which bind to FADD-FLICE complex.

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RAIDD

RIP-associated ICH-1/CED-3-homologous protein with a death domain (RAIDD) is a 23 kDa cytosolic protein that serves as the adaptor molecule that couples receptor signalling complex and ICElike cysteine proteases that cleave cellular enzymes critical to cell survival. RAIDD contains an amino-terminal domain that is homologous to the prodomain of two caspases: human ICH-1 and C. elegans CED-3. Its carboxyl-terminus contains a death domain that interacts with the homologous domain on a serine-threonine kinase component of the signalling pathway, RIP. Mutations within the amino-terminal domain of RAIDD similar to those that inactivate CED-3, prevents homophilic binding of RAIDD.

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Grb2

Growth factor receptor-bound protein 2 (Grb2), also known as Ash protein, is a 24 kDa protein that contains a central Src homology (SH2) domain flanked by two SH3 domains. Grb2 is believed to be a regulatory subunit of signaling molecules whose activity is modulated by receptor binding. Grb2 associates with activated (tyrosine phosphorylated) EGFR and PDGFR via its SH2 domain as well as IRS1, SHC, and LNK through SH2 and SH3 domains. The SH3 domain binds to SOS, a guanine nucleotide exchange factor for Ras proteins. Endocytosis of activated EGFR requires the interaction of Grb2 with the GTP binding protein dynamin, a factor essential to the formation of endocytotic vesicle. It is ubiquitously expressed and several isoforms are produced by alternative splicing. On SDS-PAGE, Grb2 has an apparent molecular weight of 28 kDa.

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Pma1

Pma1p is a plasma membrane ATPase

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Cadherin (pan)

Cadherins are calcium dependent cell adhesion molecules, which play important role in the growth and development of cells via the mechanisms of control of tissue architecture and the maintenance of tissue integrity. They are expressed in tissue specific manner and and are required for assembly of cells into solid tissue. Individual cadherin molecules are known to co-operate with each other to form a linear cell adhesion zipper. In adhesion junctions cadherins are bound to beta and gamma catenins which in turnbind to alpha catenin, an actin binding protein. Cadherins play important part in tumor invasion and metastasis.

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CD27

CD27 (50 kDa) is a member of the tumor necrosis factor (TNF) receptor superfamily. CD40 and CD30 are also members of the TNF receptor superfamily. The TNF superfamily members are known for the regulation of cell proliferation and death. In contrast to the expression of other TNFR/TNF family members, expression of CD27 and its ligand CD70 is predominantly confined to lymphocytes. High expression levels of CD27 appear to be dependent on proper ligation of antigen receptors. CD70 expression requires additional co-stimulatory and/or pro-inflammatory signals. CD27 is a membranebound receptor, but a soluble form of CD27 is also produced. Soluble CD27 is found in body fluids and can be used to monitor local and systemic immune activation. In addition, elevated serum concentrations of soluble CD27 are found in patients with B cell malignancies and soluble CD27 levels strongly correlate with tumor load.

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