TY - JOUR
T1 - Organization of the chimpanzee C4‐CYP21 region
T2 - Implications for the evolution of human genes
AU - Kawaguchi, Hiroshi
AU - Golubic, Mladen
AU - Figueroa, Felipe
AU - Klein, Jan
N1 - Copyright:
Copyright 2016 Elsevier B.V., All rights reserved.
PY - 1990/4
Y1 - 1990/4
N2 - We prepared a cosmid library from chimpanzee DNA and screened it with a mouse probe specific for the complement component 4 (C4)‐encoding gene. We isolated 29 clones and constructed restriction maps for 20 of these. The clones could be arranged into two overlapping clusters covering the entire C4 region of both chromosomes in this particular heterozygous chimpanzee. The region is about 100 kilobases (kb) long and contains two C4 and two CYP21 genes, the latter coding for the enzyme 21‐hydroxylase. Using oligonucleotide probes we identified the genes as corresponding to human C4A, C4B, CYP21 and CYP21P genes. The last gene apparently contains an 8‐base pair (bp) deletion (as does the corresponding human gene), which renders it a pseudogene. The genes are arranged in the order C4A… CYP21P… C4B… CYP21. Each of the two C4 genes is 16 kb long and thus corresponds to the short version of the human C4 genes. We suggest that the duplication of the basic C4‐CYP21 unit that generated the standard arrangement of the human C4‐CYP21 region occurred before the separation of the evolutionary lineages leading to humans and chimpanzees (i.e., more than five million years ago). We suggest further that the original form of the C4 gene was of the long variety and was generated by the insertion of a 6.8‐kb element into one of the C4 introns. The element was subsequently excised in the ancestors of the chimpanzees and in at least one lineage of the human C4B gene. We speculate that the presence of the 6.8‐kb insert in the human C4A and some C4B genes might largely be responsible for the great instability of this chromosomal region which leads to frequent duplications and deletions, some of which cause 21‐hydroxylase deficiency.
AB - We prepared a cosmid library from chimpanzee DNA and screened it with a mouse probe specific for the complement component 4 (C4)‐encoding gene. We isolated 29 clones and constructed restriction maps for 20 of these. The clones could be arranged into two overlapping clusters covering the entire C4 region of both chromosomes in this particular heterozygous chimpanzee. The region is about 100 kilobases (kb) long and contains two C4 and two CYP21 genes, the latter coding for the enzyme 21‐hydroxylase. Using oligonucleotide probes we identified the genes as corresponding to human C4A, C4B, CYP21 and CYP21P genes. The last gene apparently contains an 8‐base pair (bp) deletion (as does the corresponding human gene), which renders it a pseudogene. The genes are arranged in the order C4A… CYP21P… C4B… CYP21. Each of the two C4 genes is 16 kb long and thus corresponds to the short version of the human C4 genes. We suggest that the duplication of the basic C4‐CYP21 unit that generated the standard arrangement of the human C4‐CYP21 region occurred before the separation of the evolutionary lineages leading to humans and chimpanzees (i.e., more than five million years ago). We suggest further that the original form of the C4 gene was of the long variety and was generated by the insertion of a 6.8‐kb element into one of the C4 introns. The element was subsequently excised in the ancestors of the chimpanzees and in at least one lineage of the human C4B gene. We speculate that the presence of the 6.8‐kb insert in the human C4A and some C4B genes might largely be responsible for the great instability of this chromosomal region which leads to frequent duplications and deletions, some of which cause 21‐hydroxylase deficiency.
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U2 - 10.1002/eji.1830200405
DO - 10.1002/eji.1830200405
M3 - Article
C2 - 2347361
AN - SCOPUS:0025330547
SN - 0014-2980
VL - 20
SP - 739
EP - 745
JO - European Journal of Immunology
JF - European Journal of Immunology
IS - 4
ER -