Leucine zipper-EF-hand containing transmembrane protein 1 is a protein that in humans is encoded by the LETM1 gene.
The LETM1 protein has a transmembrane domain and a casein kinase 2 and protein kinase C phosphorylation site. The LETM1 gene is expressed in the mitochondria of many eukaryotes indicating that this is a conserved mitochondrial protein.
LETM1 is a eukaryotic protein that is expressed in the inner membrane of mitochondria. Experiments performed with human cells have been interpreted to indicate that it functions as a component of a Ca<sup>2+</sup>/H<sup>+</sup> antiporter. Experimental results with yeast cells have been interpreted as suggesting that LETM1 functions as a component of a K<sup>+</sup>/H<sup>+</sup> antiporter. The Drosophila melanogaster LETM1 protein has been shown to functionally substitute for the K<sup>+</sup>/H<sup>+</sup> antiporter function in yeast cells.
Deletion of LETM1 is thought to be involved in the development of WolfâÂÂHirschhorn syndrome in humans.