title: Cell type and developmental regulation of the fyn proto-oncogene in neural retina.
abstract: The product of the proto-oncogene c-fyn (p59fyn) is a non-receptor tyrosine kinase of unknown function. The expression of the p59fyn tyrosine kinase was analysed by immunoperoxidase staining of the different neuronal cell types in the developing chick neural retina. p59fyn was primarily localized in the cell bodies of mature retinal neurons. p59fyn immunoreactivity was most abundant in cell bodies of differentiated ganglion, amacrine and photoreceptor cells. The onset of p59fyn expression in developing photoreceptors occurred coordinately with terminal neuronal differentiation. p59fyn was also found within the outer plexiform layer, which contains synaptic terminals of the photoreceptors. At embryonic stages prior to photoreceptor differentiation, p59fyn was most highly concentrated in the cell bodies of differentiating ganglion and amacrine cells. p59fyn autokinase activity in retinal extracts decreased concomitant with the final stages of maturation of retinal neurons, suggesting that the p59fyn kinase is developmentally regulated. Thus, the expression of p59fyn is regulated in both a developmental and cell type-specific manner. The existence of p59fyn in some of the same neuronal cells as p60c-src suggests the possibility of functional redundancy of these non-receptor tyrosine kinases.
authors.affiliation: Department of Biochemistry, University of North Carolina School of Medicine, Chapel Hill 27599.
authors.forename: C A
authors.initials: CA
authors.lastname: Ingraham
authors.forename: M P
authors.initials: MP
authors.lastname: Cooke
authors.forename: Y N
authors.initials: YN
authors.lastname: Chuang
authors.forename: R M
authors.initials: RM
authors.lastname: Perlmutter
authors.forename: P F
authors.initials: PF
authors.lastname: Maness
mesh_terms: D000818:Animals; D002642:Chick Embryo; D015971:Gene Expression Regulation, Enzymologic; D010766:Phosphorylation; D010786:Photoreceptor Cells / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis*; D051076:Proto-Oncogene Proteins c-fyn; D012160:Retina / Q000166:cytology* / Q000196:embryology / Q000201:enzymology; D013570:Synaptic Membranes / Q000378:metabolism
chemical_list: D011518:Proto-Oncogene Proteins; D051076:Proto-Oncogene Proteins c-fyn