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cDNA clones of human complement components C4A and C4B alleles were prepared from mRNA obtained from the liver of a donor heterozygous at both loci. cDNA from one C4A allele was sequenced to give the derived complete amino acid sequence of 1722 amino acid residues of the C4 single chain precursor molecule and the estimated sequences of the three peptide(More)
The human complement components C4A and C4B are highly homologous proteins, but they show markedly different, class-specific, chemical reactivities. They also differ serologically in that C4A generally expresses the Rodgers (Rg) blood group antigens while C4B generally expresses the Chido (Ch) blood group antigens. C4A 1 and C4B 5 are exceptional variants(More)
Four human complement genes, which have previously been mapped between HLA-D and HLA-B on chromosome 6, have now been aligned on a 98-kilobase (kb) section of the chromosome on the basis of four overlapping cosmid clones of genomic DNA. The C2 and factor B genes, less than 2 kb apart, are about 30 kb from two C4 genes separated from each other by about 10(More)
An alternative method of isolation from human plasma is described for C3b inactivator, C3bINA, the proteinase that in conjunction with either beta 1H or C4b-binding protein will hydrolyse respectively C3b or C4b, the activation products of the third, C3 and fourth, C4, components of complement. The purification is by chromatography of plasma on columns of(More)
A remarkable difference has been observed between the reactivity of the two forms of human complement component C4. C4B binds twice as effectively as C4A to antibody-coated red cells, but the reverse occurs with protein-antigen complexes. C4B reacts much more effectively with hydroxyl groups than C4A and this is reversed for reaction with amino groups in(More)
The genes for four components (C) of complement in the human major histocompatibility complex (HLA) have been aligned previously in a series of overlapping cosmid cloned inserts. Those inserts, which contained the two C4 genes C4A and C4B, hybridized with human adrenal mRNA, indicating that they contain a gene expressed in the adrenal. The mRNA fraction of(More)