Human apolipoprotein A-I polymorphism. Identification of amino acid substitutions in three electrophoretic variants of the Münster-3 type.

摘要: Abstract Variant forms of apolipoprotein A-I (apo-A-I) have been shown to exist in the human population. One mutant form, referred as apo-A-I-Munster-3, is one charge unit more basic than normal apo-A-I on isoelectric focusing gels. This variant has same immunologic characteristics and molecular weight apo-A-I. The apo-A-I-Munster-3 from subjects three unrelated families (in two which trait be transmitted an autosomal co-dominant) analyzed by partial amino acid sequencing define cause electrophoretic abnormality. In family A, abnormality was occur smallest cyanogen bromide fragment, CB-2 (residues 87-112), revealed asparagine instead usual aspartic at residue 103. Subjects with this form no signs dyslipoproteinemia. NH2-terminal fragment (CB-1, residues 1-86) B differ electrophoretically CB-1, that a substitution arginine for proline 4 responsible form. Analysis plasma lipids affected member demonstrated percentage total cholesterol esterified somewhat lower normally observed. third family, C, having other determined yet different position. variant, histidine found 3 sequence, rather proline. all cases, could account It proposed these variants designated apo-A-I(Asp103----Asn), apo-A-I(Pro4----Arg), apo-A-I(Pro3----His), respectively, indicate accounts