Mouse type II collagen gene. Complete nucleotide sequence, exon structure, and alternative splicing

Abstract

Several overlapping clones covering the entire mouse type II collagen gene including 10 kilobases (kb) of 5'- and 15 kb of 3'-flanking sequences were isolated from a cosmid library. The overall gene structure was determined by restriction mapping and sequencing. The gene spans 28.9 kb from the start of transcription to the polyadenylation site and contains 54 exons. It codes for a major mRNA species of 4910 bases which translates into a polypeptide of 1419 amino acids. A less abundant RNA species of 5110 bases contains additional sequences corresponding to an alternatively spliced exon 2. Except for the amino-terminal propeptide (N-propeptide) domain the exon-intron organization of the mouse pro alpha 1(II) collagen gene is remarkably similar to genes for other fibrillar collagen types. The overall identity of the coding sequences of the mouse and human type II collagen genes is 89% at the nucleotide level, but only 37 amino acid changes occur within the mature alpha 1(II) collagen chains between mouse and man. Intron sizes are also conserved between the mouse and human genes but not with the chick alpha 1(II) gene. The promoter of the mouse type II collagen gene is similar to those of the rat and human genes containing a TATA box and several G + C-rich elements but no CCAAT box. The 3'-untranslated sequence contains two regions of high homology between chick, mouse, bovine, and human genes preceding the major polyadenylation site. Additional size variation in the mRNA arises from the use of a minor polyadenylation signal. Information on conserved noncoding sequences will help in studies on the regulation of the pro alpha 1(II) collagen gene. Detailed knowledge of the gene is also necessary for site-directed mutagenesis and work with transgenic mice.