Decorative receptors, membrane-binding

The second type of aberrant Fas, designated as the membrane-binding decorative receptor, which has substitutions of amino acid(s) within the EC domain, leading to an alteration of the conformation of Fas-ligand binding site (Bl), especially in cysteine-rich domains, can be anchored in the cell membrane. However, this... 

Fig. 8. Schematic representation of aberrant mFas, which is expected to attenuate the Fas-mediated signaling. Aberrant mFas is functionally and structurally classified into main three types (a) the membrane-binding decoy receptor, (b) the membrane-binding decorative receptor, and (c) the membrane-unstable or soluble receptor. Although both mFas in models (a) and (b) are normally fixed on the membrane, the mFas in the former can bind Fas ligand, but is defective for trimerization, whereas the mFas in the latter would have no ability to bind Fas ligand in vivo because of conformational alteration. Like model (a), the mFas in model (c) can be reactive for Fas ligand, but it cannot transduce the apoptotic signal into the cytoplasmic death cascade because of incomplete trimerization due to an abnormal TM domain or truncation of the 1C domain. The hatched and jagged markings indicate deduced alterations of amino acid sequence or three-dimensional structure, respectively.

In the organism, HA occurs in many diverse forms, circulating freely, decorated with a variety of HA-binding proteins (hyaladherins), tissue-associated, intercolated into the ECM by electrostatic or covalent binding to other matrix molecules. It comprises a major portion of the intimate glycocalyx that surrounds all cells. HA can be tethered to cell surfaces by any of a number of membrane-associated receptors. Recent evidence indicates that HA also exists within cells, though little is known of the form or function of such HA. 

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