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Biomedical subjects

A C Wang

Publications and source records attributed to A C Wang.

At least 127 records · Page 7Linked to original sources
PubMed1971

N-terminal amino-acid sequence of African lungfish immunoglobulin light chains.

The sequence of the N-terminal ten amino acids of the unblocked light chains derived from the low molecular weight immunoglobulin of a dipnoid fish, the African lungfish (Protopterus aethiopicus), has been determined. A degree of sequence heterogeneity as extensive as that displayed by pooled mammalian light chains was encountered. The major N-terminal sequence of the amino acids of light chains from lungfish immunoglobins can be made homologous with that of various Elasmobranchean, Chondrostean, Avian, and Mammalian species if an internal deletion of two base triplets in the gene coding for light chains from lungfish immunoglobulins is assumed. The existence of a deletion and/or insertion mechanism may have profound biological significance, since it would be ideal for the introduction of variability into immunoglobulin chains without sacrificing certain integral features of the antibody molecule.

Amino Acid Sequence↗
PubMed1971

Heavy-chain variable regions in normal and pathological immunolobulins.

Aminoacid sequence analysis of immunoglobulin G heavy chains from each of 15 normal individuals showed the presence of VHIII subgroup sequences in all individuals, to an extent of about 15-25% of the total. Therefore, different subgroups of the heavy-chain variable region are not products of alleles of a single gene.N-terminal aminoacid sequences were determined for ten heavy chains of myeloma proteins that belonged to the VHIII subgroup. Our results demonstrate the existence of a "hypervariable" region of sequence between positions 30 and 35, homologous to one of the three hypervariable regions of light chains. At several positions, variants of the basic sequence are repeated in different proteins. It is likely that such variants are derived from several recently evolved genes that constitute the VHIII subgroup.

Amino Acid Sequence↗
PubMed1970

Evidence for control of synthesis of the varible regions of the heavy chains of immunoglobulins G and M by the same gene.

Previous work indicated that the light chains of a monotypic immunoglobulins G2-K and M-K from a single patient (Ti1) are identical. Our present data show that the monotypic immunoglobulins G and M share idiotypic determinants not present in their isolated light chains or in any of a large number of other immunoglobulins tested, and that amino acid sequences of the first 27 residues from the NH(2)-terminal end of the gamma- and mu-chains are identical. These results support the hypothesis that at least two genes control the synthesis of each heavy and light chain and suggest that the monotypic immunoglobulin G and monotypic immunoglobulin M of this patient share three of the four genes involved. It is proposed that, during normal immunoglobulin synthesis, different cells of a single clone synthesize immunoglobulins M and G, and that the light chains and the variable segments of the heavy chains of the proteins of the two classes are identical within the clone. A genetic switching mechanism is suggested.

Amino Acid Sequence↗
PubMed1970

A variable region subclass of heavy chains common to immunoglobulins G, A, and M and characterized by an unblocked amino-terminal residue.

Heavy chains of IgG, IgA, and IgM classes of human immunoglobulins were compared by N-terminal residue determination and partial amino acid sequence analysis. A third subclass of the variable region of heavy chains was observed; an unblocked glutamic acid as the N-terminal residue is characteristic of this subclass. Our results indicated that the heavy chain variable region subclasses are not class specific, and that a given heavy chain variable region may be found in association with constant regions for mu-chains, alpha-chains, or gamma-chains of various subclasses.

Amino Acid Sequence↗