title: Glycine receptor internalization by protein kinases activation.
abstract: Although glycine-induced currents in the central nervous system have been proven to be modulated by protein kinases A (PKA) and C (PKC), the mechanism is not well understood. In order to better comprehend the mechanism involved in this phenomenon, we tested the PKA and PKC activation effect on the specific [(3) H]glycine and [(3) H]strychnine binding to postsynaptic glycine receptor (GlyR) in intact rat retina. The specific binding constituted about 20% of the total radioligand binding. Kinetic analysis of the specific binding exhibited a sigmoidal behavior with three glycine and two strychnine binding sites and affinities of 212 nM for [(3) H]glycine and 50 nM for [(3) H]strychnine. Specific radioligand binding was decreased (60-85%) by PKA and PKC activation, an effect that was blocked by specific kinases inhibitors, as well as by cytochalasin D. GlyR expressed in the plasma membrane decreased about 50% in response to kinases activation, which was consistent with an increase of the receptor in the microsomal fraction when PKA was activated. Moreover, immunoprecipitation studies indicated that these kinases lead to a time-dependent receptor phosphorylation. Our results suggest that in retina, GlyR is cross-regulated by G protein-coupled receptors, activating PKA and PKC.
authors.affiliation: División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510 México, D.F., México. mvflores@email.ifc.unam.mx
authors.forename: Miguel Ángel
authors.initials: MÁ
authors.lastname: Velázquez-Flores
authors.forename: Rocío
authors.initials: R
authors.lastname: Salceda
mesh_terms: D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology*; D004789:Enzyme Activation / Q000502:physiology; D005260:Female; D008297:Male; D010766:Phosphorylation / Q000502:physiology; D011485:Protein Binding / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism*; D011869:Radioligand Assay / Q000379:methods; D051381:Rats; D020318:Rats, Long-Evans; D018009:Receptors, Glycine / Q000378:metabolism*; D012160:Retina / Q000201:enzymology
chemical_list: D018009:Receptors, Glycine; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C