FULL-LENGTH AND SHORT FORMS OF UTROPHIN, THE DYSTROPHIN-RELATED PROTEIN

Ah previous studies of the localization of utrophin (the dystrophin-re lated protein) in muscle and other tissues have been performed only wi th antibodies against the C-terminal region of the protein. Since seve ral short forms of dystrophin, the apodystrophins, are produced from t he 3' end of the dystrophin gene, there is a possibility that similar short forms of utrophin exist and that these could be responsible for some of the many different localizations of 'utrophin' in muscle. We h ave produced a new panel of 15 mAbs against the N-terminal region of u trophin and me have used it together with mAbs against the C-terminal region to show that full-length utrophin is present at neuromuscular j unctions, in nerves, blood vessels and capillaries in normal muscle an d in the sarcolemma of patients with muscular dystrophy and dermatomyo sitis. However, two of the 15 mAbs also recognised rat/mouse utrophin and both of these detected an additional 62 kDa protein on Western blo ts of rat C6 glioma cells. This potential 62 kDa 'apo-utrophin' was no t detected in human cerebral cortex, in rat Schwannoma cells nor in an y of the non-nerve cells and tissues tested.