Enzyme involved in the catabolism of H(2)CO(3) but that does not mediates the reversible hydration of carbon dioxide (PubMed:19808034). Mediates complex I assembly in mitochondria and respiration. Binds HCO(3)-. Required for male fertility during anther development and dehiscence to regulate the secondary thickenings of the endothecial cell wall, probably by modulating H(2)O(2)-dependent lignin polymerization. Homotrimer. Component of the mitochondrial oxidoreductase respiratory chain complex I; element of the extra matrix-exposed domain, which is attached to the membrane arm of this complex. Interacts with GAMMACAL1 and GAMMACAL2. Probably integral to the membrane. Constitutively expressed in roots and leaves, with higher levels in flowers, particularly in tapetal tissue of anthers, inflorescence (IM) and floral meristems (FM). During flower development, first expressed in anthers and later in seeds. Reduced levels of complex I and supercomplex I + III(2) in mitochondrion. Reduced growth rates and respiration of suspension cell culture. Belongs to the gamma-class carbonic anhydrase family.