This entry represents a group of EF-hand domain-containing proteins, including EFHC1, EFHC2 and EFHB. EFHC1 has been shown to interact with microtubules to regulate cell division and cortical development []. Mutations in the EFHC1 gene has been linked to juvenile myoclonic epilepsy []. The function of EFHC2 and EFHB is not clear.
This entry represents the DM10 domain, which consists of approximately 105 residues whose function is unknown. The DM10 domain has been identified in only two types of proteins: nucleoside diphosphate kinases (which contain a single copy of the DM10 domain) and in an uncharacterised class of proteins (which contain multiple copies of DM10 domains).The nm23-H7 class of nucleoside diphosphate kinase (NDK7; ) consists of an N-terminal DM10 domain and two functional catalytic NDK domains [, ]. In Chlamydomonas, this protein (termed p40) is tightly associated with the flagellar axoneme.The DM10 domain exists in multiple copies in an uncharacterised class of proteins that includes Chlamydomonas Rib72 and mammalian EF-hand domain-containing protein 1 and EF-hand domain-containing family member C2, EFHC1/2. Rib72 and EFHC1 each contain three repeated copies of the DM10 domain followed by a C-terminal domain containing two EF-hands that are predicted to bind calcium ions. Orthologous proteins are present in many other organisms that contain motile cilia including mouse, rat, Ciona, sea urchin, Leishmania, and trypanosomes. However, no obvious Rib72/EFHC1 relative has been identified in higher plants, or in the Caenorhabditis elegans genome, which encodes only one DM10 domain-containing protein.In Chlamydomonas, and possibly mammals, DM10 domain-containing proteins are tightly bound to the flagellar doublet microtubules. This suggests that DM10 domains might act as flagellar NDK regulatory modules or as units specifically involved in axonemal targeting or assembly [, ].DM10 domains have the same organisation of secondary structural elements, a pleckstrin homology (PH)-like fold, which includes seven beta strands, with a short 3-4 residue helix after the first strand, and a more extended alpha helical region at the C terminus [, ].
