A polypeptide fractionated from plasma, urine and media of cultured cells from cystic fibrosis (CF) homozygotes and heterozygotes has been identified by its inhibition of the mucociliary system of oyster gills. Chromatography, electrophoresis, and isoelectric focusing demonstrate that the CF ciliary inhibitor (CFCI) from all sources exhibits similar biochemical characteristics. The CFCI appears to be a small cationic polypeptide of 5,000-11,000 molecular weight. Active fractions have been partially characterized by immunochemical analysis with antisera to 33 human serum proteins. Immunologic determinants of C3 (but not C3a) and several other plasma proteins have been detected by hemagglutination in both CF and analogous normal plasma fractions. Fractions containing 6 protein bands observed by acid urea polyacrylamide gel electrophoresis provided 2 isoelectrically focused sub fractions which inhibited ciliary activity. Minimum protein concentrations of plasma, urine and media fractions which elicit ciliary inhibition have been compared. Data which indicate that the CFCI segregates in CF somatic cell hybrids and that the synthesis of CFCI by heterozygous cells is approximately one half that of homozygous cells strongly suggest that the CFCI is closely related to the product of the defective gene.
|Original language||English (US)|
|State||Published - Jan 1 1976|
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