Fig. 5: GAG binding to Lcl-CTD.

a Chemical structure of chondroitin-4-sulfate (C4S) and heparin. GlcA: D-glucuronate; GalNAc(4S): N-acetyl-D-galactosamine-4-O-sulfate; IdoA(2S): α-L-iduronate-2-O-sulfate; GlcNS(6S): 6-O-sulpho-2-(sulphoamino)-D-glucosamine. b ELISA analysis of binding between immobilised mixed length C4S or heparin and wild-type (WT) and mutant (E368A, K369A, K380A, K385A, D386A, K391A) His-tagged Lcl-CTD. BSA-coated wells (−) were used as controls. Comparison of mutated Lcl-CTD to their respective WT shows a strong significant difference by two-tailed Student’s t test (***p < 0.001: K368A (heparin), K369A (C4S/heparin), K380A (C4S), K385A (C4S/heparin), K391A (C4S/heparin); **p < 0.001: K368A (C4S)) except for K380A (heparin; p = 0.241) and D386A (C4S/heparin; p = 0.588/0.931). Data are presented as mean values ± SEM derived from n = 4 biologically independent experiments. OD optical density. Source data are provided as an accompanying Source Data file. c Trimer of Lcl-CTD shown as surface representation with residues whose amides could be assigned coloured green, and those that could not be assigned coloured purple. d NMR ¹H–¹⁵N TROSY spectrum of Lcl-CTD in presence (right) or absence (left) of 0.5 mg/ml mixed length C4S. Chemical shifts that have disappeared after addition of C4S are highlighted in red, and those that display significant broadening (reduction of >85% peak intensity) are highlighted in orange. e Same information as (d) shown as a bar graph with orange bars highlighting significant peak broadening on addition of C4S. Missing assignments have a value of zero and those where peaks disappear on addition of C4S are highlighted with red circles. Source data are provided as an accompanying Source Data file. f As (d) and (e) but mapped onto the surface trimer of Lcl-CTD.