Genetic variants of human serum albumin in Italy: point mutants and a carboxyl-terminal variant.
Of the > 50 different genetic variants of human serum albumin (alloalbumins) that have been characterized by amino acid or DNA sequence analysis, almost half have been identified in Italy through a long-term electrophoretic survey of serum. Previously we have reported structural studies of 11 Italian alloalbumins with point mutations, 2 different carboxyl-terminal variants, and 1 case of analbuminemia in an Italian family. This article describes confirmation by DNA sequencing of mutations previously inferred from protein sequencing of 4 of the above alloalbumins; it also reports the mutations identified by protein and DNA sequence analysis of 4 other Italian alloalbumins not previously recorded: albumin Larino, His3-->Tyr; Tradate-2 (protein sequencing only), Lys225-->Gln; Caserta, Lys276-->Asn; and Bazzano, a carboxyl-terminal variant. The first 3 have point mutations that produce a single amino acid substitution, but a nucleotide deletion causes a frameshift and an altered and truncated carboxyl-terminal sequence in albumin Bazzano. In these 4 instances the expression of the alloalbumin is variable, ranging from 10% to 70% of the total albumiN, in contrast to the usual 50% each for the normal and mutant albumin. The distribution of point mutations in the albumin gene is nonrandom; most of the 47 reported point substitutions involve charged amino acid residues on the surface of the molecule that are not concerned with ligand-binding sites.
Department of Biology, Indiana University, Bloomington 47405.
J
J
Madison
M
M
Galliano
S
S
Watkins
L
L
Minchiotti
F
F
Porta
A
A
Rossi
F W
FW
Putnam
D000595:Amino Acid Sequence; D001483:Base Sequence; D002852:Chromatography, Ion Exchange; D004247:DNA / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D014644:Genetic Variation; D006801:Humans; D007558:Italy; D008969:Molecular Sequence Data; D017354:Point Mutation; D012709:Serum Albumin / Q000235:genetics* / Q000302:isolation & purification
D012709:Serum Albumin; D004247:DNA