Title: Extensive structural differences between genes for the α<sub>1</sub> and α<sub>2</sub> chains of type IV collagen despite conservation of coding sequences
Abstract: Analysis of the structure of the 3′‐end of the human α 2 (IV) gene demonstrated that the α 1 (IV) and α 2 (IV) genes have diverged extensively in spite of the apparent homology of the respective gene products. The NC‐1 domain and the 3′‐untranslated region are encoded by three exons in the α 2 (IV) gene but five exons in the α 1 (IV) gene. The two introns present in the NC‐ 1 domain coding part of the α 2 (IV) gene had the same location as two of the introns of the α 1 (IV) gene. The junction exon in the α 2 (IV) gene contains 53 bp coding for Gly‐X‐Y sequences whereas there are 71 bp in the α 1 (IV) gene. Three other Gly‐X‐Y coding exons studied from the human ⇌ 2 (IV) gene have sizes that differ from corresponding exons in the α 1 (IV) gene and only one intron location matches here between the two genes. None of the exons studied has 54 bp or multiples thereof.