Tektin

Tektins are cytoskeletal proteins found in cilia and flagella as structural components of outer doublet microtubules. They are also present in centrioles and basal bodies. They are polymeric in nature, and form filaments.MA Pirner and RW Linck; [http://www.jbc.org/cgi/content/abstract/269/50/31800 Tektins are heterodimeric polymers in flagellar microtubules with axial periodicities matching the tubulin lattice] ; J. Biol. Chem., Vol. 269, Issue 50, 31800-31806, Dec, 1994 ]

tructure

Tektin filaments are 2 to 3 nm diameter with two alpha helical segments. They have the consensus amino acid sequence of RPNVELCRD. Different types of tektins, designated as A (53 kDa), B (51 kDa), C (47 kDa) form dimers, trimers and oligomers in various combinations and are also associated with tubulin in the microtubule. Tektins A and B form heteropolymeric protofilaments whereas tektin C forms homodimers. Tektin filaments are present in a supercoiled state. [Peter W. Settera, Erika Malvey-Dornb, Walter Steffenc, Raymond E. Stephensd, Richard W. Linck; [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WFC-4K48KH2-3&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=89457d43ca40228c88b3a0031a1d4e09 Tektin interactions and a model for molecular functions] ; "Experimental Cell Research", Volume 312, Issue 15, 10 September 2006, Pages 2880-2896; doi:10.1016/j.yexcr.2006.05.014 ] This structure of tektins suggests that they are evolutionarily related to intermediate filaments. [J M Norrander, L A Amos, and R W Linck; [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=49961 Primary structure of tektin A1: comparison with intermediate-filament proteins and a model for its association with tubulin] ; "Proc Natl Acad Sci" U S A. 1992 September 15; 89(18): 8567–8571. ]

Function

Tektins as integral components of microtubules are essential for their structural integrity. A mutation in the "tektin-t" genes may lead to defects in flagellar activity which could manifest, for instance, as immotility of sperm leading to male infertility. [Naoko Iguchi, Hiromitsu Tanaka, Yoshihiro Nakamura, Masami Nozaki, Tsutomu Fujiwara and Yoshitake Nishimune; [http://molehr.oxfordjournals.org/cgi/content/abstract/8/6/525 Cloning and characterization of the human tektin-t gene] ; "Molecular Human Reproduction", Vol. 8, No. 6, 525-530, June 2002 ] Tektins are thought to be involved in the assembly of the basal body. [Magnus Larssona, Jan Norranderb, Susanne Gräslunda, Eva Brundellc, Richard Linckb, Stefan Ståhla, Christer Höög; [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B7GJ2-4DPMBHH-CR&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=1fdce1725164c5a0d3818329d3b15fa2 The spatial and temporal expression of Tekt1, a mouse tektin C homologue, during spermatogenesis suggest that it is involved in the development of the sperm tail basal body and axoneme] ; "European Journal of Cell Biology", Volume 79, Issue 10, October 2000, Pages 718-725; doi:10.1078/0171-9335-00097 ] The study of tektins has also been found to be useful in phylogeny, to establish evolutionary relationship between organisms. [Alaine Whinnett, Andrew V. Z. Brower, Ming-Min Lee, Keith R. Willmott, and James Mallet; [http://www.bioone.org/perlserv/?request=get-abstract&doi=10.1603%2F0013-8746(2005)098%5B0873%3APUOTAN%5D2.0.CO%3B2 Phylogenetic Utility of Tektin, a Novel Region for Inferring Systematic Relationships Among Lepidoptera] ; "Annals of the Entomological Society of America", Volume 98, Issue 6 (November 2005), Article: pp. 873–886; DOI: 10.1603/0013-8746(2005)098 [0873:PUOTAN] 2.0.CO;2] Amino acid sequences of tektins are well conserved, with significant similarity between mouse and human homologs.

ee also

* Tubulin
* Microtubule

References