Dystrophin-related protein (DRP) is an autosomal gene product with high homology to dystrophin. We have used highly specific antibodies to the unique C-terminal peptide sequences of DRP and dystrophin to examine the subcellular localization and biochemical properties of DRP in adult skeletal muscle. DRP is enriched in isolated sarcolemma from control and mdx mouse muscle, but is much less abundant than dystrophin. Immunofluorescence microscopy localized DRP almost exclusively to the neuromuscular junction region in rabbit and mouse skeletal muscle, as well as mdx mouse muscle and denervated mouse muscle. DRP is also present in normal size and abundance and localizes to the neuromuscular junction region in muscle from the dystrophic mouse model dy dy. Thus, DRP is a junction-specific membrane cytoskeletal protein that may play an important role in the organization of the postsynaptic membrane of the neuromuscular junction.
Bibliographical noteFunding Information:
K. P. C. is an Investigator of the Howard Hughes Medical Institute. J. M. E. is an MDA postdoctoral fellow. We wish to thank Suzanne Northrup for her excellent technical assistance and Dr. Kathleen Sweadner for her generous gift of antibodies. We are indebted to Dr. John P. Merlie for his gift of denervated mice. This study was supported by the MDA.