Evolutionary Dynamics of the Alpha-actinin Gene Family




Dixson, Jamie D.

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The alpha-actinin gene family is a member of the spectrin superfamily of proteins. Other members of this superfamily include the a- and ~-spectrins, ~heavy spectrin and dystrophin. Each member of this superfamily has a unique actin cross-linking distance consequent to the specific number of spectrin repeats within the central repeat region of the superfamily. Alpha-actinin is thought to be the least derived of the spectrin superfamily due to its possession of the smallest number of spectrin repeats. Though many a-actinins are known, the relationships among them are as yet undetermined. I performed phylogenetic analyses on a-actinin sequences to establish the kinship among a-actinin isoforms and to taxonomically treat the sequences. In addition, I sequenced and analyzed a previously unknown rat a-actinin 3. Analyses support four main isoforms of a-actinin. I also investigated homogenizing evolution within the spectrin repeats of the gene family. This was accomplished using gene conversion analyses and a new analysis which implements a continuum of the two known modes of homogenizing evolution: birth-and-death evolution and concerted evolution. This conceptual leap to a continuous model has not previously been made. Furthering these generalized studies of the a-actinin gene family, I used RT-PCR, cloning and automated DNA sequencing to obtain 77bp of sequence for what may be yet another member of the spectrin superfamily, the G3.5 antigen.



actin genes, spectrin


Dixson, J. D. (2001). Evolutionary dynamics of the alpha-actinin gene family (Unpublished thesis). Southwest Texas State University, San Marcos, Texas.


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