Novel amino-terminal propeptide configuration in a fibrillar procollagen undergoing alternative splicing.

Abstract

International audienceWe isolated overlapping cDNAs from embryonic libraries of the sea urchin Strongylocentrotus purpuratus coding for a fibrillar procollagen (2 alpha chain) with a predicted molecular mass of about 320 kDa. The deduced primary structure of the echinoid chain consists of a 265-amino acid carboxyl-propeptide, a triple helical domain made of 337 uninterrupted Gly-X-Y repeats, and an unusually long amino-propeptide. Aside from a 10-cysteine globular region, a collagenous sequence, and a nonhelical segment, this protein domain includes a novel 4-cysteine motif repeated several times. Interestingly, preliminary evidence indicates that different combinations of the 4-cysteine repeats are encoded by alternatively spliced transcripts. Irrespective of this, the sea urchin 2 alpha procollagen chain represents the longest fibrillar molecule identified to date by cDNA cloning experiments in both vertebrate and invertebrate organisms.We isolated overlapping cDNAs from embryonic libraries of the sea urchin Strongylocentrotus purpuratus coding for a fibrillar procollagen (2 alpha chain) with a predicted molecular mass of about 320 kDa. The deduced primary structure of the echinoid chain consists of a 265-amino acid carboxyl-propeptide, a triple helical domain made of 337 uninterrupted Gly-X-Y repeats, and an unusually long amino-propeptide. Aside from a 10-cysteine globular region, a collagenous sequence, and a nonhelical segment, this protein domain includes a novel 4-cysteine motif repeated several times. Interestingly, preliminary evidence indicates that different combinations of the 4-cysteine repeats are encoded by alternatively spliced transcripts. Irrespective of this, the sea urchin 2 alpha procollagen chain represents the longest fibrillar molecule identified to date by cDNA cloning experiments in both vertebrate and invertebrate organisms