Two exons encode the calmodulin-binding domain in the mouse phosphorylase kinase catalytic subunit gene.
The catalytic subunit, gamma, of phosphorylase kinase contains two calmodulin-binding sequences that define a domain in gamma that is homologous to the troponin-C-binding domain in troponin I. The homology is based on both sequence and functional similarities. To account for this homology, it has been proposed that the calmodulin-binding sequences in gamma and the troponin-C-binding domain in troponin I have evolved from a common ancestor. We investigated this possibility by comparing the exon structure of the gamma gene with that of troponin-I gene over their homologous domains. In the quail troponin-I gene, it is known that the entire troponin-C-binding domain is encoded by a single exon. However, two exons are found to encode the calmodulin-binding domain in the gamma gene from mouse. This result indicates that convergent evolution may be responsible for the sequence and functional similarities between the homologous domains in troponin I and gamma.
Bender
P K
PK
Department of Biochemistry and Nutrition, Virginia Polytechnic Institute, Blacksburg 24061.
Wang
Z
Z
Carlson
G M
GM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002148:Calmodulin-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D002384:Catalysis; D017931:DNA Primers; D005091:Exons; D051379:Mice; D008969:Molecular Sequence Data; D010764:Phosphorylase Kinase / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D002148:Calmodulin-Binding Proteins; D017931:DNA Primers; D010764:Phosphorylase Kinase