Fig. 6. Decreased binding of BMP2 to ß4GalT5MO proteoglycans. (A) Proteoglycans isolated from control- and ß4GalT5MO-injected embryos were resolved by 6% SDS-PAGE into two high molecular weight bands. Protein and carbohydrate content were revealed by staining with SPYRO and Pro-Q Emerald, respectively. Protein levels in each molecular weight species appear similar between control and ß4GalT5MO samples, whereas the extent of glycosylation is dramatically reduced in ß4GalT5MO embryos. (B) Proteoglycans from control-injected or ß4GalT5MO-injected embryos were bound to an affinity support and assayed for their ability to bind recombinant BMP2 and BMP7. BMP2 showed peak elution from control proteoglycans at 0.8-1.6 M NaCl. BMP2 eluted from ß4GalT5MO proteoglycans at 0.2-0.8 M NaCl. Interestingly, there was no significant difference in the ability of control or ß4GalT5MO proteoglycans to bind recombinant BMP7. Similar results were obtained using proteoglycans isolated from embryos injected with either splice-blocking (MO2) or translation-blocking (MO3) oligonucleotides.