Liprins, ELKS, and RIM-BP Proteins

The docking, priming, and fusion of vesicles take place at a specialized area of the presynaptic plasma membrane, namely the active zone. Several large multidomain proteins have been identified as being enriched at the active zone and interacting with one another in various combinations. Three widely researched protein families are Liprins, ELKS, and Rab3-interacting molecule binding proteins (RIM-BPs).

Fig.1 Domain structure of ELKS, RIM-BP, and liprin protein families. (Schoch, 2009)

Central Organizers of Active Zones

• Liprins

Liprins are a family of multi-domain scaffolding proteins that are highly evolutionarily conserved from C. elegans to humans. The liprin protein family is composed of liprins-α (1-4) and liprins-β (1-2). Studies in primary neuronal cultures showed liprins-α and KIF1A to be co-localized in various subcellular regions. As Figure 2 shown, liprins-α have also been linked to postsynaptic transport processes, playing an important role in the organization and maintenance of the synaptic ultrastructure, the transport of pre- and postsynaptic cargo, and the target selection of specific axons.

Fig.2 Role of liprins-α in neuronal transport processes. (Schoch, 2009)

• ELKS

ELKS, also known as CAZ-associated structural protein (CAST) or ERC, was named due to their high content in the amino acids glutamate (E), leucine (L), lysine (K), and serine (S). ELKS has been described as an essential regulatory subunit of the IkB kinase (IKK) complex in the nuclear factor (NF)-kB signaling cascade. It plays an important role in the regulation of synaptic vesicle fusion.

• RIM Binding Proteins

RIM-BPs are large multi-modular proteins and are composed of an N-terminal SH3 domain, three central contiguous FNIII repeats, and two tandem SH3 domains at the C-terminus. To date, protein interactions have been described only for the RIM-BP SH3 domains and the role in the regulation of secretion has been studied only in PC12 cells. All SH3 domains of RIM-BP2 have been shown to interact with L-type Ca²⁺ channel Cav1.3 and N-type Ca²⁺ channel Cav2.2.

Neurotransmitters are released by synaptic vesicle exocytosis at the active zone of a presynaptic nerve terminal. The presynaptic active zone is important for precise and fast information transfer at central nervous synapses. Numerous studies have indicated that Liprins, ELKS, and RIM-BPs are important for active zone assembly and function. If you are looking for related products such as protein, model, or ion channel related antibodies, please feel free to contact us for more information.

Reference

1. Schoch, S.; et al. Liprins, ELKS, and RIM-BP Proteins. Encyclopedia of Neuroscience. 2009, Pages 487-493.