The mouse tectorins. Modular matrix proteins of the inner ear homologous to components of the sperm-egg adhesion system.
The cDNA and derived amino acid sequences for the two major non-collagenous proteins of the mouse tectorial membrane, alpha- and beta-tectorin, are presented. The cDNA for alpha-tectorin predicts a protein of 239,034 Da with 33 potential N-glycosylation sites, and that of beta-tectorin a smaller protein of 36,074 Da with 4 consensus N-glycosylation sites. Southern and Northern blot analysis indicate alpha- and beta-tectorin are single copy genes only expressed in the inner ear, and in situ hybridization shows they are expressed by cells both in and surrounding the mechanosensory epithelia. Both sequences terminate with a hydrophobic COOH terminus preceded by a potential endoproteinase cleavage site suggesting the tectorins are synthesized as glycosylphosphatidylinositol-linked, membrane bound precursors, targeted to the apical surface of the inner ear epithelia by the lipid and proteolytically released into the extracellular compartment. The mouse beta-tectorin sequence contains a single zona pellucida domain, whereas alpha-tectorin is composed of three distinct modules: an NH2-terminal region similar to part of the entactin G1 domain, a large central segment with three full and two partial von Willebrand factor type D repeats, and a carboxyl-terminal region which, like beta-tectorin, contains a single zona pellucida domain. The central, high molecular mass region of alpha-tectorin containing the von Willebrand factor type D repeats has homology with zonadhesin, a sperm membrane protein that binds to the zona pellucida. These results indicate the two major non-collagenous proteins of the tectorial membrane are similar to components of the sperm-egg adhesion system, and, as such may interact in the same manner.
Legan
P K
PK
School of Biological Sciences, University of Sussex, Falmer, Brighton, BN1 9QG, United Kingdom.
Rau
A
A
Keen
J N
JN
Richardson
G P
GP
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002642:Chick Embryo; D018076:DNA, Complementary / Q000737:chemistry; D016326:Extracellular Matrix Proteins / Q000737:chemistry*; D005260:Female; D058851:GPI-Linked Proteins; D017403:In Situ Hybridization; D008297:Male; D008562:Membrane Glycoproteins / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry*; D051379:Mice; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D012333:RNA, Messenger; D013084:Sperm-Ovum Interactions; D013680:Tectorial Membrane / Q000737:chemistry*; D015044:Zona Pellucida / Q000737:chemistry*
D018076:DNA, Complementary; D016326:Extracellular Matrix Proteins; D058851:GPI-Linked Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D012333:RNA, Messenger; C093123:TECTB protein, human; C105350:Tecta protein, mouse