About HOMER / Homer Homolog:
Homer protein homolog 1 is a neuronal protein. In human beings, the HOMER1 gene decodes homer protein homolog 1 (Homer1).
HOMER Aliases
Homer protein homolog 1 is also known as:
●HOMER1
●HOMER1A
●HOMER1B
●HOMER1C
●Ves-l
●Homer scaffolding protein
●PSD-Zip45
Homer Homolog Structure
Homer1 protein has two terminal domains: the N-terminal EVH1 domain is involved in protein interaction and the C-terminal coiled-coil domain is involved in self-association. There are two primary splice variants: these are short-form, known as Homer1a, and long-form, known as Homer1b and Homer1c. In the Homer1a variant, there is only an EVH1 domain. The long-form variants have both EVH1 and coiled-coil domains. The coiled-coil can be broken down further into two halves, the N-terminal and the C-terminal.
When examined as a whole, the long-form Homer1 protein is said to resemble a dumbbell with two EVH1 domains positioned at the end of a coiled-coil domain.
Mammals have Homer2 and Homer3 proteins, as well as Homer1.
HOMER Function
Homer1 is expressed predominantly in the central nervous system, as well as within periphery tissue, including the kidneys, ovaries, testes, skeletal muscle and heart. Homer1 proteins work like scaffolding that forms clusters. This protein is involved in linking metabotropic glutamate receptors to other effectors to regulate the activity of mGluR.
EVH1 domain interacts with PPXXF, which is found in a host of receptors, including group 1 metabotropic glutamate receptor, IP3 receptors, Shank, transient receptor potential canonical family channels, ryanodine receptors, drebrin and dynamin3. Long-form Homer1 proteins cross-link different proteins.
Neuronal activity triggers the expression of Homer1a while Homer1b and Homer1c are constitutive. Homer1a is known as an immediate early gene and it can perform as a negative actor that blocks interaction between long-forms and their ligand proteins. Short-form Homer1 protein is therefore able to shrink dendritic structure. It is also part of the mechanism of homeostatic plasticity, which reduces activity when input rises too steeply. Coiled-coil interaction with Cdc42 prevents Cdc42 activity to reform dendritic spine structure.