A systematic nomenclature for mammalian tropomyosin isoforms

Tropomyosin, a ubiquitous protein in animals and fungi, is associated with the actin cytoskeleton and is involved with stabilising actin filaments and regulating the interaction of the filament with other actin binding proteins. The protein is best known for its role in regulating the interaction between actin and myosin in muscle contraction but in recent years its role as a major player in the organisation and dynamics of the cytoskeleton has been increasingly recognised. In mammals Tpm is expressed from four distinct genes and alternate splicing of each gene can produce a total of up to 40 different mRNA variants most of which are expressed as proteins. We are expecting a renaissance in the study of tropomyosins as the roles of these different isoforms are beginning to be deciphered. However, it is our belief that such a renaissance is being limited by confusion over the naming systems for the tropomyosin isoforms. These result in even experienced workers struggling to reconcile work done in different laboratories and at different times. We propose here a systematic nomenclature for tropomyosin based on the best current practice. We recommend the adoption of these names and a cross-reference to the table of alternate names and accession numbers for protein sequences is included here. The National Center for Biotechnology Information (NCBI) website has been amended to include the nomenclature for the human, mouse and rat genes.