The sequence of a sea urchin muscle actin gene suggests a gene conversion with a cytoskeletal actin gene |
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| Authors: | William R Crain Jr Mark F Boshar Alan D Cooper David S Durica Adam Nagy David Steffen |
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| Institution: | (1) Cell Biology Group, Worcester Foundation for Experimental Biology, 222 Maple Avenue, 01545 Shrewsbury, Massachusetts, USA;(2) Department of Chemistry, Worcester State College, 01602 Worcester, Massachusetts, USA;(3) Department of Medical Biochemistry, College of Medicine, Texas A&M University, 77843 College Station, Texas, USA;(4) Present address: Genetics Institute, 87 Cambridge Park Drive, 02140 Cambridge, Massachusetts, USA;(5) Present address: Department of Biology, University of Southern California, 90089 Los Angeles, California, USA |
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| Abstract: | Summary We report the nucleotide sequence of the single muscle actin gene of the sea urchinStrongylocentrotus purpuratus. Comparison of the protein-coding sequence of this muscle actin gene (pSpG28) with that of two linked sea urchin cytoskeletal actin genes (pSpG17 and CyIIa) reveals a region of exceptional sequence conservation from codon 61 through codon 120. Furthermore, when silent nucleotide changes are compared, the conservation of this region is still evident (7.9% silent site differences in the conserved region vs 43.3% silent site differences in the rest of the gene when pSpG28 and CyIIa are compared), indicating that the conservation is not due to particularly stringent selection on the portion of the protein encoded by this region of the genes. These observations suggest that a gene conversion has occurred between the muscle actin gene and a cytoskeletal actin gene recently in the evolution of the sea urchin genome. Gene conversion between nonallelic actin genes may thus play a role in maintaining the homogeneity of this highly conserved gene family. |
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| Keywords: | Sea urchin Actin genes Gene conversion DNA sequence Muscle actin |
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