Isoform-specific functions of Na,K-ATPase in skeletal muscle

Resumo

The published data and the results of the author’s own research in the field of the molecular and functional diversity of Na,K-ATPases are reviewed. Na,K-ATPase is an integral membrane protein that maintains the concentration gradients of Na⁺ and K⁺ that are essential for electrogenesis, excitability, and several other processes of cellular transport. Most of the Na,K-ATPase of vertebrates is found in the skeletal muscle tissue, which co-expresses the α1 and α2 isoforms of the catalytic and transport α-subunit of Na,KATPase. The activity of Na,K-ATPase is crucial for the contractile function and prolonged activity of skeletal muscle. The data that have accumulated indicate that the α1 isoform of Na,K-ATPase fulfills the major pumping function. The α2 isoform fulfills additional functions related to the specific membrane localization of the protein, the functional interactions with the proteins and lipids of the environment, and fine-tuned regulation by a variety of factors, including motor activity.