Glycoproteins of trabecular meshwork, cornea and sclera

Purpose To analyse high-molecular-weight matrix glycoproteins in trabecular meshwork, cornea and sclera using SDS/PAGE and immuno- and lectin blotting. Method Extracts of normal trabecular meshwork (TM), cornea and sclera were analysed under reducing conditions on SDS/ PAGE. Western blots were stained for total protein, and major high-molecular-weight components were identified by immunoblotting with antibodies to fibronectin (FN) and type VI collagen. Lectin blotting with PSA, MPA and DSA identified some of the glycoprotein glycans. Results FN antibody bound to the 240 kDa band in TM, cornea and sclera. Type VI collagen antibody bound more strongly to one hand and less so to two other bands at similar to 200 kDa in normal Till and to a ladder of bands in cornea and sclera. PSA and DSA bound at 240, 200 and 140 kDa in TM, cornea and sclera. MPA bound at 240, 200 and 140 kDa in TM and at 240, 200 and similar to 120 kDA in cornea and sclera. Conclusions FN is a component of the band at 240 kDA in TM, cornea and sclera. Normal Th I was found to contain relatively more of one of the isoforms of the alpha 3 (VI) chain whilst cornea and sclera contained all the alpha 3 (VI) isoforms. Complex N-linked bi/tri-antennary glycans were localised in FN and the alpha 1, alpha 2 and alpha 3 (VI) chains in TM, cornea and sclera. O-linked glycans (identified by MPA binding) were located in FN and alpha 3 (VI) chains of TM, cornea and sclera.