Myosin to actin again to repeat the cycle. The combined effect of the myriad power strokes causes the muscle to contract. The wide variety of myosin genes found throughout the eukaryotic phyla were named according to different schemes as they were discovered. The nomenclature can therefore be somewhat confusing when attempting to compare the functions of myosin proteins within and between organisms. Skeletal muscle myosin, the most conspicuous of the myosin superfamily due to its abundance in muscle fibers, was the first to be discovered. This protein makes up part of the sarcomere and forms macromolecular filaments composed of multiple myosin
Keratin used as fluorescent markers to distinguish subsets of TECs in genetic studies of the thymus. Additionally, the baleen plates of filter-feeding whales are made of keratin. Keratins (also described as cytokeratins) are polymers of type I and type II intermediate filaments, which have only been found in the genomes of chordates (vertebrates, Amphioxus, urochordates). Nematodes and many other non-chordate animals seem to only have type VI intermediate filaments, lamins, which have a long rod domain (vs. a short rod domain for the keratins). The human genome encodes 54 functional keratin genes which are located in two clusters on chromosomes 12