Phosphoglycerate mutase in mammalian striated muscles: subcellular localization and binding partners.

Contrary to previously published data, we have found that in mammalian skeletal muscles, phosphoglycerate mutase (PGM) is organized in a regular, striated fashion within the sarcomere. In the absence of the enzyme effectors, PGM localizes mainly at the M-line, but under conditions typical for contracting muscle, the enzyme accumulates within the I-band of the sarcomere. Searching for muscle PGM binding partners, we have found that PGM interacts with several enzymes of triose phosphate metabolism. It might suggest that PGM is a central structural element of the muscle glycolytic complex located within the isotropic region of the sarcomere.