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IMMUNOGLOBULIN GAMMA CHAINS OF A MONOTREME MAMMAL, THE ECHIDNA ( TACHYGLOSSUS ACULEATUS ): AMINO ACID COMPOSITION AND PARTIAL AMINO ACID SEQUENCE
Author(s) -
Atwell J. L.,
Marchalonis J. J.
Publication year - 1977
Publication title -
international journal of immunogenetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.41
H-Index - 47
eISSN - 1744-313X
pISSN - 1744-3121
DOI - 10.1111/j.1744-313x.1977.tb00617.x
Subject(s) - monotreme , biology , amino acid , biochemistry , peptide sequence , antibody , immunoglobulin light chain , glycine , immunoglobulin heavy chain , genetics , botany , gene , taxonomy (biology) , systematics
SUMMARY The echidna represents the lowest stage in phytogeny at which molecules clearly homologous to IgG antibodies appear to occur. We provide evidence that a fraction of γ chains possess an unblocked N terminal sequence comparable to the V HIII sub‐group of human γ chains and that glycine is the C‐terminal residue. Statistical comparison of amino acid composition of the component chains with other immunoglobulin heavy chains suggests that echidna γ chains are more closely related to eutherian γ chains than to the 7S Ig heavy chains from amphibia or aves. The results are consistent with our view that true γ‐type heavy chains did not appear in evolution until after the mammalian line diverged from the stem reptiles.