Don R. Barnett

Localization of the haptoglobin α and β genes (HPA and HPB) to human chromosome 16q22 by in situ hybridization

Human haptoglobin (Hp) is a protein that binds free hemoglobin and circulates in plasma of vertebrates as a tetrachain (αβ)2 structure. This study maps HPA and H

Amino-acid substitution in haemoglobin I (Texas variant).

AN electrophoretically fast genetic variant of adult haemoglobin was described in six members of a Negro family living in Texas by Thompson et al. in 1963 (ref. 1). Fingerprints of the purified haemoglobin established the identity of this variant with haemoglobin I previously described by Murayama and Ingram2, in which the third tryptic peptide from the N-terminus of the α chain contained an amino-acid alteration responsible for the rapid electrophoretic migration of the intact haemoglobin. Lysine, which is the sixteenth residue, had been replaced in haemoglobin I by an acidic amino-acid. The substitution was described in both I variants from Texas1 and Philadelphia3 as being lysine to aspartic acid; however, recent elucidation of the genetic code has eliminated the substitution lys→asp from the class of mutations which could result from alteration of a single nucleotide base in the triplet code4. A nucleotide triplet coding for lysine (AAA or AAG) could not be altered in a single base so that it would specify aspartic acid (GAU or GAC). This led Beale and Lehmann5 to re-examine the I variant from Philadelphia. Their findings established the substitution to be lys→glu, which is in agreement with an alteration in a single nucleotide (AAA or AAG to GAA or GAG).

Organization and Chromosomal Locations of Genes Encoding Human Plasma Proteins

Abstract Recombinant DNA technology has provided the means to examine and characterize human genes encoding plasma proteins. Three families of genes have been studied in our laboratory: haptoglobin–a member of the serine protease family, transferrin–a major member of a gene family important in iron transport and the Group-Specific Component–recently discovered to be a member of the albumin gene family. The chromosomal locations, evolutionary relationships, DNA polymorphisms and post-translational processing of these plasma proteins have been emphasized in the studies described.