Functional and morphological stasis during molecular evolution.
The evolutionary distance between two sets of proteins was estimated using the techniques of Miyata and Yasunaga (1980) and Kimura (1980). Human beta 2-microglobulin was compared with the homologous murine molecule, while human and equine alpha-globin were similarly treated. It was found that a large amount of molecular evolution has occurred in beta 2-microglobulin since its divergence from the common ancestor of mice and humans. Kimura's estimate of evolutionary distance, K, is 0.353, while those of Miyata and Yasunaga are KS = 0.708 and KA = 0.171. The respective values for human and equine alpha-globin are 0.152, 0.293, and 0.084. In spite of this molecular evolution, it is shown that murine beta 2-microglobulin can effect the expression of HLA class I antigens on the surface of human-mouse hybrid cells and that the tertiary structures of human and equine deoxyhemoglobin are nearly identical. These observations are discussed in the light of Kimura's theory of neutral allelic drift.
Williams
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Department of Anthropology, Arizona State University, Tempe 85287-2402.
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D003062:Codon / Q000235:genetics; D004247:DNA / Q000235:genetics; D005914:Globins / Q000235:genetics*; D006736:Horses / Q000235:genetics*; D006801:Humans; D051379:Mice / Q000235:genetics*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D001613:beta 2-Microglobulin / Q000235:genetics*
D003062:Codon; D001613:beta 2-Microglobulin; D005914:Globins; D004247:DNA