FITC-labeled I-protein specifically binds to A-bands and/or Z-lines of glycerinated myofibrils of chicken breast muscle.
Ion-exchange column-purified I-protein was labeled by fluorescein isothiocyanate (FITC) at an equimolar ratio. When FITC-labeled I-protein was reacted with glycerinated myofibrils of chicken breast muscle in a phosphate-buffered saline, fluorescence was observed at the A-band and/or the Z-line of the sarcomere. However, FITC-labeled I-protein did not stain freshly prepared myofibrils. When FITC-I-protein was reacted with a nitrocellulose paper sheet on which muscle proteins were blotted after SDS-polyacrylamide gel electrophoresis, some peptide bands, including connectin and nebulin, were fluorescent. These facts can explain why anti-I-protein antibodies stain the A-I junctional region of fresh myofibrils and A-bands and/or Z-lines of glycerinated myofibrils. It is very likely that I-protein is transferred from the A-I junctions of myofibrils and translocates to A-bands and Z-lines, where some components that can bind to I-protein are localized, as myofibrils are degraded during the glycerination.
D000818:Animals; D001665:Binding Sites; D002645:Chickens; D016650:Fluorescein-5-isothiocyanate; D005452:Fluoresceins; D005990:Glycerol / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism*; D009210:Myofibrils / Q000378:metabolism*; D013861:Thiocyanates
D005452:Fluoresceins; D009124:Muscle Proteins; D013861:Thiocyanates; D016650:Fluorescein-5-isothiocyanate; D005990:Glycerol