Colocalization of the genes for the alpha 3(IV) and alpha 4(IV) chains of type IV collagen to chromosome 2 bands q35-q37.
Each type of basement membrane in man contains between two and five genetically distinct type IV collagens: alpha 1(IV)-alpha 5(IV). Genes for alpha 1(IV), alpha 2(IV), alpha 3(IV), and alpha 5(IV) have been isolated. We have recently isolated partial cDNAs for the fifth member of the family, designated alpha 4(IV). On the basis of comparison of the deduced peptide sequences of all five chains, the type IV collagens can be divided into two families: alpha 1-like, comprising alpha 1(IV), alpha 3(IV), and alpha 5(IV); and alpha 2-like, comprising alpha 2(IV) and alpha 4(IV). Genes encoding the alpha 1(IV) and alpha 2(IV) chains (COL4A1 and COL4A2) both map to human chromosome 13q34 and have been shown to be transcribed from opposite DNA strands using a common bidirectional promoter that allows coordinate regulation of the two chains. Indeed, these two chains are commonly found together in basement membrane and form [alpha 1]2.[alpha 2] heterotrimers. Whereas alpha 1(IV) and alpha 2(IV) have been found in all basement membranes studied hitherto, it has been shown that alpha 3(IV) and alpha 4(IV) are found in only a subset of basement membranes. In basement membranes where either of these molecules is present, however, they are found together. In view of this relationship and the structural similarities between alpha 1(IV) and alpha 3(IV) and between alpha 2(IV) and alpha 4(IV), we hypothesized that COL4A3 and COL4A4, the genes encoding alpha 3(IV) and alpha 4(IV), respectively, have a genomic organization similar to that of COL4A1 and COL4A2.(ABSTRACT TRUNCATED AT 250 WORDS)
Mariyama
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Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06536-0812.
Zheng
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Yang-Feng
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Reeders
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D001485:Basement Membrane / Q000378:metabolism; D005075:Biological Evolution; D002874:Chromosome Mapping; D002889:Chromosomes, Human, Pair 2; D003094:Collagen / Q000235:genetics* / Q000378:metabolism; D004247:DNA / Q000235:genetics; D015342:DNA Probes; D005786:Gene Expression Regulation; D006801:Humans; D006822:Hybrid Cells; D005810:Multigene Family
D015342:DNA Probes; D003094:Collagen; D004247:DNA