Ry proteins. Tubulins. Tubulins are the key structural components of microtubules and they come in many forms in eukaryotes. In the T. thermophila genome, phylogenetic analysis of tubulin homologs reveals the presence of one or two genes, each within the essential alpha, beta, and gamma subfamilies and one in each of the delta, epsilon, and eta, which are found in organisms that possess centrioles/basal bodies. In addition, T. thermophila encodes nonorder UPF 1069 canonical tubulin homologs that can be divided into two categories. In the first category are genes that are most similar to the canonical a- or b-tubulins. These nine genes lack characteristic motifs for the tail domain post-translational modifications that are essential to the function of their canonical counterparts. Three of the b-like genes form a tandem cluster with intergenic intervals of less than 2 kb. We hypothesize that these genes function, perhaps redundantly, in formation or function of some of the many highly specialized microtubule systems of T. thermophila cells. Experimental analysis of BLT1, a b-like tubulin, indicated that its product localizes to a small subset of microtubules and is not incorporated into growing ciliary axonemes. Genetic deletion of this gene or of the a-like gene TTHERM_00647130 did not yield an obvious phenotype. The second category of noncanonical tubulin homologs consists of three novel proteins that fall into a clade with P. tetraurelia iota tubulin. Two of these are closely related to each other and closely linked in the genome and thus likely arose by a recent tandem duplication. The functions of these genes are unknown, but because they are, so far, unique to ciliates, they might be responsible for microtubule functions specific to this phylum. Dyneins. Dyneins, which were first discovered in Tetrahymena, are molecular motors that translocate along microtubule tracks, a process critical to many activities in T. thermophila including ciliary beating, karyokinesis, MAC division, cortical organization, and phagocytosis. For the most part, the families of T. thermophila dynein subunits appear to be similar to those of other model organisms; however, there are some interesting differences. T. thermophila light MedChemExpress PTK/ZK chains LC3A and 3B are most similar to the green alga Chlamydomonas reinhardtii’s LC3 and LC5. These proteins belong to the larger PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19858302 family of thioredoxin-related proteins, and, without biochemical evidence identifying one or both of 
the proteins as part of a dynein complex, it may be premature to label these as dynein components. Light chain LC4 belongs to the calmodulin-related family of proteins and may regulate Tetrahymena thermophila Genome Sequence calcium-dependent ciliary reversal. T. thermophila expresses two LC4 genes, perhaps providing alternative or additional ways to control ciliary motility compared to species that express only one. In other systems, LC8 is associated with several different dynein and nondynein complexes, and T. thermophila expresses one canonical LC8 as well as five divergent LC8-like genes, with unknown functions. Perhaps the most interesting revelation is that T. thermophila expresses 25 dynein heavy chains. These include the 14 DYH genes previously described and 11 new ones, all of which appear to be axonemal. The complexity of the DYH family may represent a mechanism by which the organism can fine-tune ciliary activity, produce specialized cilia, and/or generate large numbers of new cilia quickly. Along these.Ry proteins. Tubulins. Tubulins are the key structural components of microtubules and they come in many forms in eukaryotes. In the T. thermophila genome, phylogenetic analysis of tubulin homologs reveals the presence of one or two genes, each within the essential alpha, beta, and gamma subfamilies and one in each of the delta, epsilon, and eta, which are found in organisms that possess centrioles/basal bodies. In addition, T. thermophila encodes noncanonical tubulin homologs that can be divided into two categories. In the first category are genes that are most similar to the canonical a- or b-tubulins. These nine genes lack characteristic motifs for the tail domain post-translational modifications that are essential to the function of their canonical counterparts. Three of the b-like genes form a tandem cluster with intergenic intervals of less than 2 kb. We hypothesize that these genes function, perhaps redundantly, in formation or function of some of the many highly specialized microtubule systems of T. thermophila cells. Experimental analysis of BLT1, a b-like tubulin, indicated that its product localizes to a small subset of microtubules and is not incorporated into growing ciliary axonemes. Genetic deletion of this gene or of the a-like gene TTHERM_00647130 did not yield an obvious phenotype. 
The second category of noncanonical tubulin homologs consists of three novel proteins that fall into a clade with P. tetraurelia iota tubulin. Two of these are closely related to each other and closely linked in the genome and thus likely arose by a recent tandem duplication. The functions of these genes are unknown, but because they are, so far, unique to ciliates, they might be responsible for microtubule functions specific to this phylum. Dyneins. Dyneins, which were first discovered in Tetrahymena, are molecular motors that translocate along microtubule tracks, a process critical to many activities in T. thermophila including ciliary beating, karyokinesis, MAC division, cortical organization, and phagocytosis. For the most part, the families of T. thermophila dynein subunits appear to be similar to those of other model organisms; however, there are some interesting differences. T. thermophila light chains LC3A and 3B are most similar to the green alga Chlamydomonas reinhardtii’s LC3 and LC5. These proteins belong to the larger PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19858302 family of thioredoxin-related proteins, and, without biochemical evidence identifying one or both of the proteins as part of a dynein complex, it may be premature to label these as dynein components. Light chain LC4 belongs to the calmodulin-related family of proteins and may regulate Tetrahymena thermophila Genome Sequence calcium-dependent ciliary reversal. T. thermophila expresses two LC4 genes, perhaps providing alternative or additional ways to control ciliary motility compared to species that express only one. In other systems, LC8 is associated with several different dynein and nondynein complexes, and T. thermophila expresses one canonical LC8 as well as five divergent LC8-like genes, with unknown functions. Perhaps the most interesting revelation is that T. thermophila expresses 25 dynein heavy chains. These include the 14 DYH genes previously described and 11 new ones, all of which appear to be axonemal. The complexity of the DYH family may represent a mechanism by which the organism can fine-tune ciliary activity, produce specialized cilia, and/or generate large numbers of new cilia quickly. Along these.