Characterization of the mouse gene for the alpha 1 chain of type XVIII collagen (Col18a1) reveals that the three variant N-terminal polypeptide forms are transcribed from two widely separated promoters.
The mouse gene for the alpha 1 chain of type XVIII collagen (Col18a1) is more than 102 kb and consists of 43 exons. Type XVIII collagen transcripts encode polypeptides that differ with respect to three variant N-terminal noncollagenous domains that are 301 (NC1-301), 517 (NC1-517), or 764 (NC1-764) residues in length. Characterization of genomic clones revealed that the three variant NC1 domains result from the use of two alternative promoters, separated by a distance of 50 kb. The upstream promoter, promoter 1, directs the synthesis of the NC1-301 domain in conjunction with exons 1 and 2, whereas the downstream promoter, promoter 2, directs that of the NC1-517 and NC1-764 domains in conjunction with exon 3, with the latter two variants differing with respect to alternative splicing of the exon 3 sequences. Exons 4-9 encode a portion of the NC1 domain shared by all three polypeptide variants, and exons 9-43 encode the common collagenous and C-terminal noncollagenous sequences. The marked differences previously observed in the expression of variant type XVIII collagen transcripts in mouse tissues thus result from tissue-specific use of these two promoters.
Rehn
M
M
Department of Medical Biochemistry, University of Oulu, Finland.
Hintikka
E
E
Pihlajaniemi
T
T
D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003094:Collagen / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005796:Genes / Q000235:genetics*; D007438:Introns / Q000235:genetics; D007668:Kidney / Q000737:chemistry; D008099:Liver / Q000737:chemistry; D008168:Lung / Q000737:chemistry; D051379:Mice; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic / Q000235:genetics
D012333:RNA, Messenger; D003094:Collagen