The lengthening of a giant protein: when, how, and why?
Subcommissural organ (SCO)-spondin is a giant glycoprotein of more than 5000 amino acids found in Vertebrata, expressed in the central nervous system and constitutive of Reissner's fiber. For the first time, in situ hybridization performed on zebrafish (Danio rerio) embryos shows that the gene encoding this protein is expressed transitionally in the floor plate, the ventral midline of the neural tube, and later in the diencephalic third ventricle roof, the SCO. The modular organization of the protein in Echinodermata (Strongylocentrotus purpuratus), Urochordata (Ciona savignyi and C. intestinalis), and Vertebrata (Teleostei, Amphibia, Aves and Mammalia) is also described. As the thrombospondin type 1 repeat motifs represent an increasingly large part of the protein during Deuterostomia evolution, the duplication mechanisms leading to this complex organization are examined. The functional significance of the particularly well-preserved arrangement of the series of SCO-spondin repeat motifs and thombospondin type 1 repeats is discussed.
Faculté de Médecine, INSERM/UMR 384, 28 place Henri Dunant, Clermont-Ferrand cedex, France.
Olivier
O
Meiniel
Robert
R
Meiniel
Fabrice
F
Lalloué
Robert
R
Didier
Marie-Odile
MO
Jauberteau
Annie
A
Meiniel
Daniel
D
Petit
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000737:chemistry* / Q000145:classification* / Q000235:genetics; D016384:Consensus Sequence; D017124:Conserved Sequence; D019143:Evolution, Molecular; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D020449:Repetitive Sequences, Amino Acid; D015027:Zebrafish / Q000196:embryology / Q000378:metabolism; D029961:Zebrafish Proteins / Q000737:chemistry* / Q000145:classification* / Q000235:genetics
D015816:Cell Adhesion Molecules, Neuronal; C108402:SCO-spondin; D029961:Zebrafish Proteins