Mutations in sarcoglycans (SGs) cause autosomal-recessive limb-girdle muscular dystrophy. SGs exist as a complex of four transmembrane proteins (a, b, c, and d). We have recently shown that a-SG is an ecto-ATPase, i.e. an enzyme able to hydrolyze extracellular ATP. The ecto-ATPase activity and assembly of the SG complex was examined in heterologous expression systems. Individual or all four SGs were expressed in HEK 293 and COS-1 cells by using different expression vectors. Our results show that in COS-1 cells localisation to cell membrane of the SG complex requires the contemporary expression of all four isoforms. In contrast, a-SG can be expressed alone in HEK cells and its localization at cell membrane determines the de novo appearance of ecto-ATPase activity. Funded by TELETHON ITALY and NIH.
Sarcoglycan heterologous expression.
SANDONA', DORIANNA;FRASSON I;MARTINELLO, TIZIANA;
2004
Abstract
Mutations in sarcoglycans (SGs) cause autosomal-recessive limb-girdle muscular dystrophy. SGs exist as a complex of four transmembrane proteins (a, b, c, and d). We have recently shown that a-SG is an ecto-ATPase, i.e. an enzyme able to hydrolyze extracellular ATP. The ecto-ATPase activity and assembly of the SG complex was examined in heterologous expression systems. Individual or all four SGs were expressed in HEK 293 and COS-1 cells by using different expression vectors. Our results show that in COS-1 cells localisation to cell membrane of the SG complex requires the contemporary expression of all four isoforms. In contrast, a-SG can be expressed alone in HEK cells and its localization at cell membrane determines the de novo appearance of ecto-ATPase activity. Funded by TELETHON ITALY and NIH.Pubblicazioni consigliate
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