RXYLT1 and congenital muscular dystrophy: Further, recombinant TMEM5 was able to transfer radiolabeled Xyl from UDP-Xyl to α-DG-Fc340 expressed in a CMD patient cell line with a homozygous mutation in TMEM5 but was not able to effectively transfer to α-DG-340 when the putative M3 sites (TPT, 317–319, converted to APA) were eliminated.