We report the identification by two hybrid screens of two novel similar proteins, called Arabidopsis thaliana gamma carbonic anhydrase like1 and 2 (AtgammaCAL1 and AtgammaCAL2), that interact specifically with putative Arabidopsis thaliana gamma Carbonic Anhydrase (AtgammaCA) proteins in plant mitochondria. The interaction region that was located in the N-terminal 150 amino acids of mature AtgammaCA and AtgammaCA like proteins represents a new interaction domain. In vitro experiments indicate that these proteins are imported into mitochondria and are associated with mitochondrial complex I as AtgammaCAs. All plant species analyzed contain both AtgammaCA and AtgammaCAL sequences indicating that these genes were conserved throughout plant evolution. Structural modeling of AtgammaCAL sequences show a deviation of functionally important active site residues with respect to gammaCAs but could form active interfaces in the interaction with AtgammaCAs. We postulate a CA complex tightly associated to plant mitochondrial complex.