Mutational analysis of the cytoplasmic tail of the human transferrin receptor. Identification of a sub-domain that is required for rapid endocytosis.

127

Section: Signals Contributed By/3 Subunitsmentioning

confidence: 89%

An ion-transporting ATPase encodes multiple apical localization signals.

Gottardi

Caplan

1993

127

“…Other sequences capable of controlling the internalization of other surface receptors, i.e., the transferrin receptor, have also been proposed (Chen et al, 1990;Lazarovits and Roth, 1988;Ktistakis et al, 1990;Collawn et al, 1990;Bansal and Giersasch, 1991;Lobel et al, 1989;Girones et al, 1991). At present, the only common features of these sequences are the presence of one aromatic residue and their specification of a particular structure: a tight type 1/3 turn.…”

Section: Discussionmentioning

confidence: 99%

“…But, are these necessary events sufficient for the internalization of the insulin receptor in response to insulin binding? Since an amino acid sequence present in the juxtamembrane domain of various receptors could play a role in their endocytosis (Chen et al, 1990;Lazarovits and Roth, 1988;Ktistakis et al, 1990;Collawn et al, 1990;Bansal and Giersasch, 1991;Lobel et al, 1989;Girones et al, 1991), we focused our interest on the juxtamembrane domain of the ~-subunit of the insulin receptor. In CHO ceils expressing the A960 mutant receptor (a deletion of 12 amino acids in the juxtamembrane domain (amino acids 954-965, which include the above-mentioned amino acid sequence), receptor autophosphorylation was normal or near normal (Fig.…”

Section: ~I-insulin Internalization In Cho Cells Expressing Normal or Mutated Insulin Receptorsmentioning

confidence: 99%

“…Class I receptors, which include transport protein receptors (i.e., LDL, transferrin, asialoglycoprotein receptors), move spontaneously to clathrin-coated pits and are continuously internalized and recycled even in the absence of ligand. The preferential localization of class I receptors to clathrincoated pits is presumably dependent on the cytoplasmic domain of these receptors (Brown et al, 1983) and various sequences putatively capable of controlling the internalization of different cell surface receptors have been proposed (Chen et al, 1990;Lazarovits and Roth, 1988;Ktistakis et al, 1990;Collawn et al, 1990;Bansal and Giersasch, 1991;Lobel et al, 1989;Girones et al, 1991). The only common features of these sequences identified thus far are the presence of aromatic residues and the propensity of the amino acid involved to form exposed fight beta turns.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Two steps of insulin receptor internalization depend on different domains of the beta-subunit [published erratum appears in J Cell Biol 1993 Nov;123(4):1047]

Carpentier

Paccaud

Backer

et al. 1993

Abstract. The internalization of signaling receptors such as the insulin receptor is a complex, multi-step process. The aim of the present work was to determine the various steps in internalization of the insulin receptor and to establish which receptor domains are implicated in each of these by the use of receptors possessing in vitro mutations. We find that kinase activation and autophosphorylation of all three regulatory tyrosines 1146, 1150, and 1151, but not tyrosines 1316 and 1322 in the COOH-terminal domain, are required for the ligand-specific stage of the internalization process; i.e., the surface redistribution of the receptor from microvilli where initial binding occurs to the nonvillous domain of the cell. Early intracellular steps in insulin signal transduction involving the activation of phosphatidylinositol Y-kinase are not required for this redistribution. The second step of internalization consists in the anchoring of the receptors in clathrincoated pits. In contrast to the first ligand specific step, this step is common to many receptors including those for transport proteins and occurs in the absence of kinase activation and receptor autophosphorylation, but requires a juxtamembrane cytoplasmic segment of the ~-subunit of the receptor including a NPXY sequence. Thus, there are two independent mechanisms controlling insulin receptor internalization which depend on different domains of the #-subunit.

“…Although deletion of the entire domain inhibits the localization of receptors to coated pits (Goldstein et al, 1985;Lehrman et al, 1985;Iacopetta et al, 1988;Mostov et al, 1986). efficient endocytosis has been shown in several cases to require only 20-30 amino acids of the cytoplasmic region (Cben et al, 1990;Lobel et al, 1989;Girones et al, 1991). In a number of receptors, aromatic residues in the cytoplasmic juxtamembrane region are necessary for coated pit-mediated endocytosis (Davis et al, 1987;Lazrovits and Roth, 1988;Lobel et al, 1989;Jing et al, 1990;Breitfeld et al, 1990;Johnson et al, 1990;Valiquette et al, 1990;McGraw et al, 1991;Fuhrer et al, 1991).…”

mentioning

confidence: 99%

The insulin receptor juxtamembrane region contains two independent tyrosine/beta-turn internalization signals.

Backer

Shoelson

Weiss

et al. 1992

100

Abstract. We have investigated the role of tyrosine residues in the insulin receptor cytoplasmic juxtamembrahe region (Tyr953 and Tyro) during endocytosis. Analysis of the secondary structure of the juxtarnembrahe region by the Chou-Fasman algorithms predicts that both the sequences GPLY953 and NPEY~ form tyrosine-containing E-turns. Similarly, analysis of model peptides by 1-D and 2-D NMR show that these sequences form E-turns in solution, whereas replacement of the tyrosine residues with alanine destabilizes the E-turn. CHO cell lines were prepared expressing mutant receptors in which each tyrosine was mutated to phenylalanine or alanine, and an additional mutant contained alanine at both positions. These mutations had no effect on insulin binding or receptor autophosphorylation. Replacements with phenylalanine had no effect on the rate of [nsI]insulin endocytosis, whereas single substitutions with alanine reduced [125I]insulin endocytosis by 40-50%. Replacement of both tyrosines with alanine reduced internalization by 70%. These data suggest that the insulin receptor contains two tyrosine//3-turns which contribute independently and additively to insulin-stimulated endocytosis.