Glycoproteins insulin receptor

Concanavalin A is a plant lectin from the jack bean (Canavalia ensiformis) which binds with high affinity to mannose residues of glycoproteins. Concanavalin A is known to stimulate the tyrosine kinase activity of the INSR (3-subunit with consecutive activation of kinases downstream the insulin receptor (IRS, PI 3-kinase). It is believed that Concanavalin A stimulates the activation and autophosphorylation of the INSR kinase through aggregation of the receptor, although the precise mechanism of action is unclear. 

Kirkpatrick RB, Matico RE, McNulty DE, Strickler JE, Rosenberg M 1995 An abundantly secreted glycoprotein from Drosophila melanogaster is related to mammalian secretory proteins produced in rheumatoid tissues and by activated macrophages. Gene 153 147-154 Leconte I, Carpentier JL, Clauser E 1994 The functions of the human insulin receptor are affected in different ways by mutation of each of the four N-glycosylation sites in the fl subunit. J Biol Chem 269 18062-18071... 

The insulin receptor is a tetrameric integral membrane glycoprotein consisting of two 735 amino acid a-chains and two 620 amino acid P-chains. These are held together by disulfide linkages (Figure 11.2). The a-chain resides entirely on the extracellular side of the plasma membrane and contains the cysteine-rich insulin-binding domain. 

INSR insulin receptor MOG myelin-oligodendrocyte glycoprotein... 

The insulin receptor (Figure 16.15) is a transmembrane glycoprotein of two types of subunits connected by disulfide bridges. Two large (130 kD) extend extracellularly, where they form the insulin-binding of the two /3 subunits (90 kD) contains a transmembrane segment sine kinase domain. 

The insulin receptor (Figure 23.15) is a glycoprotein with an 012/ 2 tetrameric structure, stabilized by... 

Piovant, M. and Lena, P. (1988) Membrane glycoproteins immunologically related to the human insulin receptor are associated with presumptive neuronal territories and developing neurones in Drosophila melanogaster. Development 103 145-156. 

An abnormal membrane glycoprotein that is associated with malignancy in a wide range of different tumours binds to both concanavalin A and to wheat-germ agglutinin. Several physical parameters of this glycoprotein resemble those of the insulin receptor. 

Although the details of the chemical composition of the insulin receptors are not known, treatment of membranes with various enzymes has revealed that the receptor is a glycoprotein. A drastic digestion by trypsin markedly reduces the binding of insulin to the membrane by destroying the receptor sites, milder digestion only reduces the affinity of the binding without receptor destruction. 

The insulin receptor in rat liver membranes has been found to interact with another membrane glycoprotein that may represent either a non-recognition portion of the receptor oligomer, or an effector molecule related to the biological action of insulin. ... 

Methods of traversing the basolateral membrane include uptake systems for organic cations and anions via fadhtated diffusion and/or active transport [1]. Organic anions and cations cross the basolateral membrane via ATP-driven or secondary active processes (H -antiport) [2]. Basolateral uptake processes include the gamma-glutamyl transport system [3] and those for glycoproteins [4]. Certain proteins (insulin, epidermal growth factor (EGF)) are transcytosed across the tubular cells from the blood to the tubular lumen via receptor-mediated uptake [5]. 

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