This is the C-terminal domain of Armadillo-like helical domain-containing protein 3 (ARMH3), the previously uncharacterised peripheral Golgi protein C10orf76. ARMH3 interacts with and is involved in GBF1 recruitment, Golgi maintenance and protein secretion [, ]. C10orf76 associates with the lipid kinase PI4KB that increases phosphatidylinositol 4-phosphate (PI4P) levels at the Golgi, being essential for the viral replication of specific enteroviruses []. The function of this domain is unknown.
The calcium-binding domain found in S100, CaBP7/8 and similar proteins mainly from animals. It is a subfamily of the EF-hand calcium-binding domain []. S100s are small dimeric acidic calcium and zinc-binding proteins abundant in the brain, with S100B playing an important role in modulating the proliferation and differentiation of neurons and glia cells []. S100 proteins have two different types of calcium-binding sites: a low affinity one with a special structure, and a 'normal' EF-hand type high-affinity site.Protein S100-G from humans (formerly known as Calbindin-D9k) also belong to this family of proteins, but it does not form dimers. CaBP-9k is a cytosolic protein expressed in a variety of tissues. Although its precise function is unknown, it appears to be under the control of the steroid hormones oestrogen and progesterone in the female reproductive system []. In the intestine, this protein may be involved in calcium absorption by mediating intracellular diffusion [].Calcium-binding protein 8 from Rattus norvegicus (Rat) regulates Golgi-to-plasma membrane trafficking by interacting with PI4KB and inhibiting its activity. It may play a role in the physiology of neurons and is potentially important in memory and learning []. A number of these proteins are known to bind calcium while others are not. This entry represents the region of the EF-hand high affinity site but makes no assumptions on the calcium-binding properties of this site.
