Molecular cloning and protein structure of a human blood group Rh polypeptide.

Abstract

cDNA clones encoding a human blood group Rh polypeptide were isolated from a human bone marrow cDNA library by using a polymerase chain reaction-amplified DNA fragment encoding the known common N-terminal region of the Rh proteins. The entire primary structure of the Rh polypeptide has been deduced from the nucleotide sequence of a 1384-base-pair-long cDNA clone. Translation of the open reading frame indicates that the Rh protein is composed of 417 amino acids, including the initiator methionine, which is removed in the mature protein, lacks a cleavable N-terminal sequence, and has no consensus site for potential Nglycosylation. The predicted molecular mass of the protein is 45,500, while that estimated for the Rh protein analyzed in NaDodSO4/polyacrylamide gels is in the range of 30,000-32,000. These findings suggest either that the hydrophobic Rh protein behaves abnormally on NaDodSO4 gels or that the Rh mRNA may encode a precursor protein, which is further matured by a proteolytic cleavage of the C-terminal region of the polypeptide. Hydropathy analysis and secondary structure predictions suggest the presence of 13 membrane-spanning domains, indicating that the Rh polypeptide is highly hydrophobic and deeply buried within the phospholipid bilayer. In RNA blot-hybridization (Northern) analysis, the Rh cDNA probe detects a major 1.7-kilobase and a minor 3.5-kilobase mRNA species in adult erythroblasts, fetal liver, and erythroid (K562, HEL) and megakaryocytic (MEG01) leukemic cell lines, but not in adult liver and kidney tissues or lymphoid (Jurkat) and promyelocytic (HL60) cell lines. These results suggest that the expression of the Rh gene(s) might be restricted to tissues or cell lines expressing erythroid characters.

The Structure and Function of the Rh Antigen Complex

“…[16][17][18][19] The genes each have ten exons, are 97% identical, and arose via gene duplication. RhD and RhCE proteins differ by 32-35 of 416 amino acids (Fig.…”

Molecular basis of the D variant phenotypes DNU and DII allows localization of critical amino acids required for expression of Rh D epitopes epD3, 4 and 9 to the sixth external domain of the Rh D protein

“…The protein has close homology to the Rh CcEe proteins with 35 or 36 amino acid substitutions (Avent et al, 1990;Cherif-Zahar et al, 1990). It is alterations in conformation induced in the Rh D protein by these amino acid changes which create the epitopes which comprise the D antigen.…”

“…All three full-length clones were found to have a single base substitution at codon 353 (GGA → AGA) (Gly → Arg) (Fig 2). Two Rh ce (encoding Pro103, Ala226) and one Rh cE (encoding Pro103, Pro226) clones were fully sequenced, and found to have no sequence differences to the original Rh cDNA clone (Avent et al, 1990;Cherif-Zahar et al, 1990), except for those encoding Ala226 in the Rhce clones.…”

Determination of the Rh factor: A practical illustrating the use of the polymerase chain reaction

“…Individuals possessing this molecule were called Rh positive and the remaining 15% Rh negative [1]. This was the basis for the human Rhesus blood group system, which more than 60 years after its discovery is, next to ABO, the most clinically significant in transfusion medicine [2].The Rh locus consists of two structural genes, D and CcEe, which code for the polypeptide chain D and the proteins C/c and E/e, respectively [3,4]. The presence or absence of gene D in the genome determines the genetic basis for the polymorphism of the Rh-positive/Rh-negative blood groups.…”

“…The Rh locus consists of two structural genes, D and CcEe, which code for the polypeptide chain D and the proteins C/c and E/e, respectively [3,4]. The presence or absence of gene D in the genome determines the genetic basis for the polymorphism of the Rh-positive/Rh-negative blood groups.…”