DS-epi1-deficient NC- and epidermis-enriched explants (Fig. 7C), which suggests that reduced IdoA levels do not alter the expression of integrins. In some mammalian cell types, it has been reported that the α5 and β1 integrin subunits (Veiga et al., 1997; Franco et al., 2009) and Sdc4 (Shworak et al., 1994; Deepa et al., 2004; Holmborn et al., 2012) are hybrid PGs that carry both CS and HS chains; however, it is not known whether they contain CS/DS chains. To investigate whether migratory CNC cells also synthesize IdoA in CS/DS chains, we isolated CNC explants at stage 18 and cultivated the cells in vitro in [35S]-containing medium for 24 h to label the PGs. Chase B degraded 47% of the labeled CS/DS PGs, which covered a wide range of molecular mass of over 18 kDa (Fig. 7D), and the size distribution of the degraded products indicated that isolated IdoA moieties are present in the native chains. The molecular mass of the IdoA-containing PGs is compatible with integrin α5β1 subunits (120-150 kDa) (Alfandari et al., 2003) and Sdc4 (40-250 kDa) (Gopal et al., 2010). However, we could not identify CS, CS/DS and HS chains on endogenous integrin α5 and β1 in Xenopus
