Proteoglycans, GAGs, and serglycin core proteins of platelets. Samples were analyzed on 4% to 20% gradient SDS-PAGE gels. Eluates of 4 × 108 platelets were applied to each lane. Proteoglycans and GAGs are stained with Alcian blue and appear as smears on the gels. No samples were applied to lanes that are not marked. (A) The 0.8 M NaCl DEAE-Sephacel eluates from WT and KO PGs are shown. Gel also stained with Coomassie blue revealed several sharp protein bands. A high Mr proteoglycan with 2 components was present in the WT platelets. No proteoglycans were visible on the gel of KO platelets. (B) Intact and 0.2 M NaOH-digested proteoglycans. C4S is shark chondroitin 4-sulfate. Lanes left to right: KO PGs, WT PGs, blank lane, KO GAGs, WT GAGs after NaOH digestion. A vertical line has been inserted to indicate a repositioned lane containing the C4S standard. (C) Immunoblot of SG core protein from 2.3 × 108 WT platelets per lane, one mouse per lane. (D) Lanes 1 and 2: PGs from SG+/− mice. (E) Lane 1: Intact PGs from 0.8 M NaCl eluate from WT platelets. Lane 2: 0.8 M NaCl eluate from KO platelets. Lane 3: 0.8 M/0.2% TX-100 eluate, WT platelets. Lanes 4–5: 0.8 M NaCl/0.2% TX-100 eluate from SG+/− platelets. Lane 6: 0.8 M NaCl/0.2% TX-100 eluate from KO platelets.
