InterPro domain: IPR038081

The calx-beta motif is present as a tandem repeat in the cytoplasmic domains of Calx Na-Ca exchangers, which are used to expel calcium from cells. This motif overlaps domains used for calcium binding and regulation. The calx-beta motif is also present in the cytoplasmic tail of mammalian integrin-beta4, which mediates the bi-directional transfer of signals across the plasma membrane, as well as in some cyanobacterial proteins. This motif is also found in Fras1/Frem family of extracellular proteins (extracellular matrix organizing protein FRAS1 and FRAS1-related extracellular matrix proteins FRAM1, 2 and 3) required for proper organogenesis during embryonic development and whose mutations lead to Fraser Syndrome, a rare congenital disorder characterised by multisystem malformation usually comprising abnormal brain formation, cryptophthalmos, syndactyly and renal defects [ 1 ]. This motif contains a series of beta-strands and turns that form a self-contained beta-sheet [ 2 , 3 ].

1. Behavioural effects of extracellular matrix protein Fras1 depletion in the mouse. Eur J Neurosci
2. Calx, a Na-Ca exchanger gene of Drosophila melanogaster. Proc. Natl. Acad. Sci. U.S.A. 94, 10249-54
3. The recently reported NIbeta domain is already known as the Calx-beta motif. Trends Biochem. Sci. 24, 260