RESUMO
Analysis of the primary structure of the rabbit skeletal muscle ryanodine receptor led to the identification of two molecules of 5032 and 5037 residues, respectively. Such a sequence discrepancy is likely to be due to the alternative splicing of a 15 bp exon (1) encoding a 5 amino acid insertion (Ala-Gly-Asp-Ala-Gln) after residue 3479. By using PCR on first strand cDNA, we searched for the 15 base pair insertion in the ryanodine receptor mRNA from adult slow- and fast-twitch skeletal muscle, as well as from fast-muscles, at various stages of post-natal development. All rabbit skeletal muscle mRNAs, regardless of their developmental stage and twitch properties, contain two RYR transcripts, suggesting the coexistence of two RYR isoforms in mammalian skeletal muscle.
Assuntos
Envelhecimento/metabolismo , Processamento Alternativo , Canais de Cálcio/biossíntese , Expressão Gênica , Fibras Musculares de Contração Rápida/metabolismo , Fibras Musculares de Contração Lenta/metabolismo , Proteínas Musculares/biossíntese , Rianodina/metabolismo , Sequência de Aminoácidos , Animais , Animais Recém-Nascidos , Sequência de Bases , Canais de Cálcio/análise , Primers do DNA , Éxons , Dados de Sequência Molecular , Desenvolvimento Muscular , Fibras Musculares de Contração Rápida/crescimento & desenvolvimento , Fibras Musculares de Contração Lenta/crescimento & desenvolvimento , Proteínas Musculares/análise , RNA Mensageiro/análise , RNA Mensageiro/biossíntese , Coelhos , Canal de Liberação de Cálcio do Receptor de Rianodina , Transcrição GênicaRESUMO
Motor nerves can only modify the phenotype of muscle fibres within a myogenically determined range. The particular range of a given fibre is an intrinsic property of that fibre, depending on the type of muscle (limb or jaw) and the specific tag imprinted upon it during development.
