Evidence for several gamma-carboxyglutamic acid-containing proteins in dentin.

With anion-exchange chromatography, the gamma-carboxyglutamic acid (Gla)-containing proteins of rat dentin were separated into four closely related fractions (gamma 1-gamma 4). Edman degradation of gamma 2 gave two NH2-terminal sequences with a minor sequence beginning five residues shorter than the major one. Gel electrophoresis of gamma 2 yielded one major and one minor protein band. Fraction gamma 3 gave one band on gel electrophoresis and a single NH2-terminal sequence. The composition of gamma 4 suggested that, compared to gamma 2 and gamma 3, a portion of the COOH-terminal was missing. Thus some of the heterogeneity of rat dentin Gla-containing proteins can be explained by shortened ends.