ISSN:
0886-1544
Keywords:
multitubulin hypothesis
;
neighbor-joining method
;
ciliate
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
We have cloned and sequenced the two β-tubulin genes of the ciliated protozoan Tetrahymena thermophila. The two genes encode identical 443 amino acid peptides which are 99.7% identical to the β-tubulin proteins of T. pyriformis and 95% identical to human β1 tubulin. T. thermophila contains only one β-tubulin gene (Callahan et al., 1984: Cell 36:441-445). Thus, all of the extremely diverse microtubule structures in this unicellular organism can be formed from a single α- and a single β-tubulin peptide. We have also carried out a phylogenetic analysis of 84 complete β-tubulin peptide sequences. This analysis supports two hypotheses regarding β-tubulin evolution and function: (1) Multifunctional β-tubulins are under greater evolutionary constraint than β-tubulins present in specialized cells or in cells with very few microtubule related functions, which can evolve rapidly; and (2) Cells which form axonemes maintain a homogeneous population of tubulins. © 1993 Wiley-Liss, Inc.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cm.970250305
