SHISA9 antibody

Background of SHISA9 antibody

Cytosine-knot AMPAR modulating protein 44 (CKAMP44) is a novel protein that was recently identified as a brain-specific type 1 transmembrane protein that associates with AMPA receptors in synaptic spines (1). AMPA receptors (AMPARs) mediate fast synaptic transmissions in the vertebrate central nervous system (2). AMPARs are composed of four types of subunits, named as GluR1, GluR2, Glur3, and GluR4, which combine to form tetramers (3, 4). Several AMPAR-interacting proteins have been identified that affect the receptors’ subcellular localization, synaptic stabilization, and kinetics, these include transmembrane AMPAR regulatory proteins (TARPs), Sol-1 and cornichons (5-7). CKAMP44, located on human and mouse chromosome 16, was recently identified as another AMPAR-interacting protein (1). CKAMP44 was shown to modulate short-term plasticity at some excitatory synapses. In Xenopus Oocytes, expression of CKAMP44 reduced GluR1 and GluR2 mediated steady-state currents, but it did not affect kainite or NMDA receptor-mediated currents (1). CKAMP44 contains an extracellular N-terminal cysteine-rich motif with eight cysteines that are highly conserved across vertebrate species. Six of these eight cysteine residues might function as stabilizers for the Cys-knot structure of the CKAMP44 (1). RT-PCR analysis from various mouse tissues RNA revealed two splice variants, CKAMP44a and CKAMP44b, which differ by only 48 bases (1). This CKAMP44-specific antibody recognizes both splice variants. Its expression is restricted to the brain; its mRNA is present in most brain structures during embryonic and postnatal development. CKAMP44a is approximately a 52kDa protein (432 amino acids) and CKAMP44b is approximately a 49kDa protein (407 amino acids).