Invitrogen™ Connexin 43 Monoclonal Antibody (CX-1B1)

Description

CX-1B1 is specific for one of the unphosphorylated forms of Connexin 43. This antibody was at one time thought to be specific for all unphosphorlyated forms of Connexin 43, but that can no longer be claimed since it was discovered that Connexin 43 can be phosphorylated at multiple sites. Recent studies have shown that phosphorylation occurs at a serine within the epitope recognized by this antibody. CX-1B1 recognizes Connexin 43 only when the serine at residue 368 is unphosphorylated. CX-1B1 will, however, recognize Connexin 43 if it is phosphorylated at sites besides Ser368. In some cell types, cross-reactivity with a ~70 kDa protein of unknown identity has been observed. This cross-reactivity is likely due to a shared epitope. Reactivity has been confirmed by western blot analysis of extracts derived from dog heart, human heart, mouse brain, mouse heart, rat brain, and Clone 9 (C1-9) rat liver cells. Clone 9 is the recommended positive control for CX-1B1. This antibody has also been used in immunofluorescence applications and immunolocalization of Connexin 43, however, for immunohistochemical applications polyclonal Rabbit anti-Connexin 43 (Cat. No. 71-0700) is recommended.

Connexin 43 (Cx43) is a member of the gap junction protein family. Connexins assemble as a hexamer and are transported to the plasma membrane to create a hemichannel that can associate with hemichannels on nearby cells to create cell-to-cell channels. Clusters of these channels assemble to make gap junctions. Gap junction communication is important in development and regulation of cell growth. Phosphorylation of Cx43 is important in regulating assembly and function of gap junctions. Ser368 of Cx43 is phosphorylated by protein kinase C (PKC) after activation by phorbol esters, which decreases cell-to-cell communication. Src can interact with and phosphorylate Cx43 to alter gap junction communication. GFAP are membrane-spanning proteins that facilitate the transfer of ions and small molecules between cells. According to sequence similarities at the nucleotide and amino acid levels, the gap junction proteins are divided into two categories, alpha and beta. Connexin 43 is the major protein of gap junctions in the heart, and gap junctions are thought to have a crucial role in the synchronized contraction of the heart and in embryonic development. Connexin 43 is also targeted by several protein kinases that regulate myocardial cell-cell coupling. A related intron-less connexin 43 pseudogene, GJA1P, has been mapped to chromosome 5. Mutations in the GFAP gene cause X-linked Charcot-Marie-Tooth disease, an inherited peripheral neuropathy, oculodentodigital dysplasia and heart malformations. Alternatively spliced transcript variants of GFAP have been found.