Translation elongation factor eEF1A binds to a novel myosin binding protein-C-like protein

Eukaryotic translation elongation factor 1A (eEF1A) is a guanine-nucleotide binding protein, which transports aminoacylated tRNA to the ribosomal A site during protein synthesis. In a yeast two-hybrid screening of a human skeletal muscle cDNA library, a novel eEF1A binding protein, immunoglobulin-like and fibronectin type III domain containing 1 (IGFN1), was discovered, and its interaction with eEF1A was confirmed in vitro. IGFN1 is specifically expressed in skeletal muscle and presents immunoglobulin I and fibronectin III sets of domains characteristic of sarcomeric proteins. IGFN1 shows sequence and structural homology to myosin binding protein-C fast and slow-type skeletal muscle isoforms. IGFN1 is substantially upregulated during muscle denervation. We propose a model in which this increased expression of IGFN1 serves to down-regulate protein synthesis via interaction with eEF1A during denervation.