Developmental changes in the type I procollagen processing pathway in chick-embryo cornea.
Type I procollagen processing in chick-embryo corneas was studied at days 12, 14 and 17 of development. Pulse-chase experiments and electrophoretic analysis of salt-soluble extracts showed developmental changes in the processing pathway. A kinetic model was fitted to the data to determine rate constants for processing of both N- and C-propeptides. Data for pro alpha 1(I)-chain processing and pro alpha 2(I)-chain processing were fitted separately (where pro means procollagen). Between days 12 and 17 the relative flux through the pC-collagen (procollagen chain lacking the N-propeptide) and pN-collagen (procollagen chain lacking the C-propeptide) pathways increased approx. 4-fold. Pro alpha 1(I) chains and pro alpha 2(I) chains were processed by slightly different routes. Variations in the rate constants were compared with electron-microscopic measurements of collagen fibril diameters at each stage of development. Diameters increased by less than 10% over the period from 12 to 17 days. It was concluded that fibril diameters are relatively insensitive to the pathway of procollagen processing in the salt-soluble pool.
Mellor
S J
SJ
Department of Biochemistry, University of Edinburgh Medical School, Scotland, U.K.
Atkins
G L
GL
Hulmes
D J
DJ
D000818:Animals; D002642:Chick Embryo; D003094:Collagen / Q000737:chemistry; D003315:Cornea / Q000737:chemistry* / Q000196:embryology / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D010434:Pepsin A; D011347:Procollagen / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational
D011347:Procollagen; D003094:Collagen; D010434:Pepsin A