A novel noncollagenous protein encoded by an alternative transcript of the chick type III collagen gene is expressed in cartilage, bone and muscle.
We have identified a noncollagenous protein, Col3alt, encoded by an alternative transcript of the chick type III collagen gene; its amino acid sequence is out of frame with the collagen coding sequence. This 178-amino-acid protein is unique and has no recognizable motifs other than a hydrophobic domain. Col3alt is found in embryonic cartilage, muscle and bone and in the proliferative and prehypertrophic zones of juvenile chicken growth plates. The protein is intracellular in immature chondrocytes and myoblasts, but is extracellular in well-differentiated cartilage, muscle and bone, despite the lack of a conventional signal peptide. These results demonstrate an unexpected economy of genome utilization in which a single gene, using alternative promoters, gives rise to two unrelated proteins, type III collagen and Col3alt.
Cohen
Arthur J
AJ
Department of Biochemistry, School of Dental Medicine, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6003, USA. art@biochem.dental.upenn.edu
Lakshmi
T R
TR
Niu
Zeling
Z
Trindade
Janine
J
Billings
Paul C
PC
Adams
Sherrill L
SL
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001842:Bone and Bones / Q000196:embryology*; D002356:Cartilage / Q000196:embryology*; D002455:Cell Division; D002642:Chick Embryo; D003001:Cloning, Molecular; D024061:Collagen Type III / Q000737:chemistry / Q000235:genetics*; D018076:DNA, Complementary / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D005091:Exons; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009132:Muscles / Q000196:embryology*; D016366:Open Reading Frames; D011401:Promoter Regions, Genetic; D013997:Time Factors
D024061:Collagen Type III; D018076:DNA, Complementary