title: Light-induced tyrosine phosphorylation of BIT in the rat suprachiasmatic nucleus.
abstract: Circadian changes of protein tyrosine phosphorylation in the hypothalamic suprachiasmatic nucleus have been studied using rats maintained under 12-h light/ 12-h dark cycles as well as constant dark conditions. We found that tyrosine phosphorylation of BIT (brain immunoglobulin-like molecule with tyrosine-based activation motifs), a transmembrane glycoprotein of 90-95 kDa, was higher in the light period than in the dark period and was increased after light exposure in the dark period. Similar changes in tyrosine phosphorylation were observed under constant dark conditions, but its amplitude was weaker than that in 12-h light/12-h dark cycles. As the tyrosine-phosphorylated form of BIT is able to bind to the Src homology 2 domain of a protein tyrosine phosphatase, SHP-2, we examined association of these proteins in suprachiasmatic nucleus extracts and found that SHP-2 was coprecipitated with BIT in parallel with its tyrosine phosphorylation. These results suggest that tyrosine phosphorylation of BIT might be involved in light-induced entrainment of the circadian clock.
authors.affiliation: Division of Protein Metabolism, Institute for Protein Research, Osaka University, Osaka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nakahata
authors.forename: N
authors.initials: N
authors.lastname: Okumura
authors.forename: T
authors.initials: T
authors.lastname: Shima
authors.forename: M
authors.initials: M
authors.lastname: Okada
authors.forename: K
authors.initials: K
authors.lastname: Nagai
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation; D002940:Circadian Rhythm / Q000502:physiology; D003624:Darkness; D015180:Electrophoresis, Gel, Two-Dimensional; D008029:Lighting; D008297:Male; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008970:Molecular Weight; D039842:Neural Cell Adhesion Molecule L1; D019006:Neural Cell Adhesion Molecules / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D010775:Photic Stimulation; D051381:Rats; D017208:Rats, Wistar; D011971:Receptors, Immunologic; D015398:Signal Transduction / Q000502:physiology; D013493:Suprachiasmatic Nucleus / Q000737:chemistry / Q000201:enzymology*; D014443:Tyrosine / Q000378:metabolism*; D018909:src Homology Domains / Q000502:physiology
chemical_list: D000943:Antigens, Differentiation; D008562:Membrane Glycoproteins; D039842:Neural Cell Adhesion Molecule L1; D019006:Neural Cell Adhesion Molecules; D011971:Receptors, Immunologic; D014443:Tyrosine; D020928:Mitogen-Activated Protein Kinases