title: Critical Role for an acidic amino acid region in platelet signaling by the HemITAM (hemi-immunoreceptor tyrosine-based activation motif) containing receptor CLEC-2 (C-type lectin receptor-2).
abstract: CLEC-2 is a member of new family of C-type lectin receptors characterized by a cytosolic YXXL downstream of three acidic amino acids in a sequence known as a hemITAM (hemi-immunoreceptor tyrosine-based activation motif). Dimerization of two phosphorylated CLEC-2 molecules leads to recruitment of the tyrosine kinase Syk via its tandem SH2 domains and initiation of a downstream signaling cascade. Using Syk-deficient and Zap-70-deficient cell lines we show that hemITAM signaling is restricted to Syk and that the upstream triacidic amino acid sequence is required for signaling. Using surface plasmon resonance and phosphorylation studies, we demonstrate that the triacidic amino acids are required for phosphorylation of the YXXL. These results further emphasize the distinct nature of the proximal events in signaling by hemITAM relative to ITAM receptors.
authors.affiliation: Centre for Cardiovascular Sciences, Institute for Biomedical Research, The College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom. c.e.hughes@bham.ac.uk
authors.forename: Craig E
authors.initials: CE
authors.lastname: Hughes
authors.forename: Uma
authors.initials: U
authors.lastname: Sinha
authors.forename: Anjali
authors.initials: A
authors.lastname: Pandey
authors.forename: Johannes A
authors.initials: JA
authors.lastname: Eble
authors.forename: Christopher A
authors.initials: CA
authors.lastname: O'Callaghan
authors.forename: Steve P
authors.initials: SP
authors.lastname: Watson
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D001792:Blood Platelets / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D007700:Kinetics; D037181:Lectins, C-Type / Q000737:chemistry / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D020349:Surface Plasmon Resonance; D000072377:Syk Kinase; D014443:Tyrosine / Q000737:chemistry*; D014757:Viper Venoms / Q000737:chemistry; D051746:ZAP-70 Protein-Tyrosine Kinase / Q000737:chemistry
chemical_list: D000596:Amino Acids; C104778:CLEC2B protein, human; D047908:Intracellular Signaling Peptides and Proteins; D037181:Lectins, C-Type; D008562:Membrane Glycoproteins; D014757:Viper Venoms; C112292:rhodocytin protein, Calloselasma rhodostoma; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; D051746:ZAP-70 Protein-Tyrosine Kinase; C497261:ZAP70 protein, human