Rowth plate cartilage (Table 1). GlcNAc 1?4GlcUA 1?Gal 1?Gal 1?4Xyl(2-O-phosphate) was lately demonstrated to become formed by EXTL2 and regarded to be a biosynthetic intermediate of an immature GAG chain (25). Furthermore, the truncated linkage pentasaccharide GalNAc 1?4GlcUA 1?Gal 1?Gal 1?4Xyl(2-O-phosphate)-2AB was not detected in any of the growth plate cartilage tissues examined. GlcUA 1?Gal 1?Gal 1?Xyl-2AB, GlcUA 1?Gal 13Gal 1?Xyl(2-O-phosphate)-2AB, and GlcNAc 1?GlcUA 13Gal 1?Gal 1?Xyl(2-O-phosphate)-2AB had been digested with alkaline phosphatase; -glucuronidase, which catalyzes hydrolysis of -GlcUA residues in the non-reducing termini of sugar chains; heparitinase, which cleaves the 1? linkage of GlcNAc 1?GlcUA (three, 25); and chondroitinase AC-II, which cleaves the 1? linkage of GalNAc 1?GlcUA, resulting in coelution with each authentic standard (data not shown). These results indicate that ChGn-1 could possibly preferentially transfer GalNAc for the κ Opioid Receptor/KOR supplier phosphorylated linkage tetrasaccharide inside the protein linkage region of CS. A Phosphorylated Tetrasaccharide Structure Facilitates ChGn-1-transferase Activity–We subsequent examined no matter if transfer of a GalNAc residue for the phosphorylated linkage tetrasaccharide structure GlcUA 1?Gal 1?Gal 1?4Xyl(2-Ophosphate) was preferentially catalyzed by ChGn-1. We used -TM bearing a tetrasaccharide (GlcUA-Gal-Gal-Xyl) as a primer and recombinant FAM20B as an enzyme source to create a phosphorylated linkage structure, GlcUA-GalGal-Xyl(2-O-phosphate), attached to -TM. This phosphorylated structure (GlcUA-Gal-Gal-Xyl(2-O-phosphate)-TM) was incubated with ChGn-1 and UDP-[3H]GalNAc as a donor subJOURNAL OF BIOLOGICAL CHEMISTRYRegulation of Chondroitin Sulfate Chain NumberTABLE 2 Comparison of your acceptor specificity of ChGn-1 or co-transfection of ChGn-1 and XYLP secreted into culture medium by transfected COS-1 cellsGalNAc-transferase activitya Acceptor substrate GlcUA-Gal-Gal-Xyl-thrombomodulin GlcUA-Gal-Gal-Xyl(2P)-thrombomodulinb GlcUA-Gal-Gal-Xyl-O-Ser-Gly-Trp-Pro-Asp-Gly GlcUA-Gal-Gal-Xyl(2P)-O-Ser-Gly-Trp-Pro-Asp-Glya b cTABLE three Comparison of phosphatase activities of XYLP and co-transfected XYLP and Drug Metabolite Chemical site ChGn-Substrate GlcUA-Gal-Gal-Xyl(2P)-TMa b cXYLP UDP-GalNAcb nmol/mg/h NDcXYLP/ChGn-1a nmol/mg/h 4.5 0.ChGn-1 0.05 1.34 NDc NDChGn-1/XYLPpmol/mg/h 0.01 0.06 0.01 0.eight 1.8 0.2 ND 62.six 5.The value is the mean S.D. of two measurements. 2P represents 2-O-phosphate. Not detected ( 0.01 nmol/mg/h).The values will be the imply S.D. of three measurements. 2P represents 2-O-phosphate. ND, not detected ( 0.01 pmol/mg/h).A Pull-downIgG-Seph Ni TA one hundred kDa WB mouse IgGstrate. As shown in Table two, the GalNAcT-I activity of ChGn-1 for GlcUA-Gal-Gal-Xyl-(2-O-phosphate)-TM was more than 100-fold larger than for GlcUA-Gal-Gal-Xyl-TM. These results indicate that ChGn-1 preferentially transfers a GalNAc residue for the phosphorylated tetrasaccharide in vitro. Interactions involving ChGn-1 and XYLP–We showed previously that GalNAc-GlcUA-Gal-Gal-Xyl(2-O-phosphate) was not detected in cells (3). Moreover, as shown in Table 1, GalNAc-GlcUA-Gal-Gal-Xyl(2-O-phosphate)-2AB was not detected in ChGn-1 / , ChGn-2 / , and wild-type growth plate cartilage. This recommended that ChGn-1-mediated addition of GalNAc may be accompanied by XYLP-dependent dephosphorylation throughout completion with the linkage pentasaccharide formation. To evaluate the interactions between ChGn-1 and XLYP, ChGn-1 and XLYP had been co-expressed. We 1st examined no matter whether the co-expre.