Use of consensus oligonucleotides for detecting and isolating nucleic acids encoding calcium binding domains of the troponin C superfamily.
Proteins belonging to the troponin C superfamily (troponin C, calmodulin, myosin light chains, and parvalbumin) are involved in a wide variety of cellular activities mediated by calcium ions. Most of these proteins bind ionic calcium, and all have calcium binding domains that are conserved to some extent at the nucleic acid level. We made use of the conservation in the third calcium binding domain to synthesize two consensus sequence oligonucleotide probes, one 43 bases and the other 25 bases long. By using cDNA and genomic clones encoding calmodulin, troponin C, parvalbumin, and the sea urchin Spec proteins, we show that these probes hybridize with nucleic acid sequences representing calcium binding domains. In an RNA gel blot analysis of embryonic RNA from the sea urchin Strongylocentrotus purpuratus, we show that transcripts which have previously been shown to encode troponin C like proteins hybridize with the consensus sequence probes. Screening sea urchin cDNA and genomic libraries with the 43-base consensus oligonucleotide shows that the probe can be used to isolate cloned nucleic acids. Two such genomic clones from a Lytechinus pictus library were isolated and characterized. One clone encodes part of an L. pictus calmodulin gene, and the other encodes a member of the superfamily that has not been characterized previously. The consensus oligonucleotides should be valuable probes in the diagnosis and isolation of nucleic acids encoding proteins of the troponin C superfamily.