Connexin protein

Regarding the pH sensor, the carboxy tail length has been demonstrated as a determinant of pH sensitivity [Liu et al., 1993]. Further investigations [Morley et al., 1996] revealed a new model of intramolecular interactions in which the carboxy terminal serves as an independent domain that, under certain conditions, can bind to another separate domain of the connexin protein (e.g. a region including His-95) and close the channel, comparable to the ball-and-chain model for potassium channels. In this receptor (His-95),... 

Falk MM, Kumar NM, Gilula NB Biosynthetic membrane integration of connexin proteins in Kanno Y, Kataoka K, Shiba Y Shibata Y, Shimazu T (eds) Intercellular Communication through Gap Junctions. Progress in Cell Research, vol 4. Amsterdam, Elsevier, 1995, pp 319-322. 

Warner A, Clements DK, Parikh S, Evans WH, DeHaan RL Specific motifs in the external loops of connexin proteins can determine gap junction formation between chick heart myocytes. J Physiol (Lond) 1995 488 721-728. 

Layer/Cell Type Gap Junctions" Connexin mRNA Connexin Protein References... 

Krutovskikh VA, Mesnil M, Mazzoleni G, et al. 1995. Inhibition of rat liver gap junction intercellular communication by tumor-promoting agents in vivo Association with aberrant localization of connexin proteins. Lab Invest 72 571-577. 

The Gap Junction Channel, Connexin Protein, and Their Importance for Electrochemical Studies... 

Connexin protein is unique in forming a gated pore through two membranes. Two questions particular to this structure are (1) how is the junctional channel assembled (e.g., how do the two hemichannels find each other and interact to form a stable structure) and (2) what is the interaction between... 

Figure 2. Proposed structural organization of connexin proteins into the plasma membrane to form a connexon unit. Panel A Each hemi-connexon is composed of six identical protein units arranged to circle the water filled pore, hemi-connexons dock with equivalent structures in adjacent cells to form an intact gap junction. Panel B topography of the connexin 43 protein in the plasma membrane. There are believed to be four trans-membrane spanning domains, the third of which is believed to line the water filled pore. The two extra-cellular loops are believed to dock with equivalent loops donated by connexins from the adjacent cell. (From [27] with permission).

New information has been added in appropriate chapters on hpid rafts and caveolae, aquaporins, connexins, disorders due to mutations in genes encoding proteins involved in intracellular membrane transport, absorption of iron, and conformational diseases and pharmacogenomics. 

Rogers, M., J. M. Berestecky, M. Z. Hossain et al. 1990. Retinoid-enhanced gap junctional communication is achieved by increased levels of connexin 43mRNA and protein. Mol Carcinog 3(6) 335-343. 

Connexin 43 is one of the cell membrane gap junction proteins that allow for cell to cell communication. Cancer cell transformation is correlated with the loss of Connexin 43 expression (Hussain et al. 1989, Zhang et al. 1992). Lycopene increased Connexin 43 expression in fetal skin fibroblasts (Stahl et al. 2000), oral cancer KB-1 cells grown in organotypic rafts (Livny et al. 2003) and breast cancer cell lines (Chalabi et al. 2007). 

Lauf, U., Lopez, P. and Falk, M. M. (2001). Expression of fluorescently tagged connexins A novel approach to rescue function of oligomeric DsRed-tagged proteins. FEBS Lett. 498, 11-5. 

Another, but less well defined, class of molecules, some of whose members mediate adhesion interaction, is the four-transmembrane domain family, which shares similar hydropathy plots and may have similar dispositions with respect to the phospholipid bilayer, for example the myelin proteolipid proteins, the connexins of gap junctions, the ryanodine receptor and others. 

The rat cell line R3/1 was established from cells obtained from broncho-alveolar tissues of foetal Wistar rats at 20 days of gestation. This cell line displays a phenotype with several characteristic features of ATI cells. R3/1 cells were analysed to show a positive expression for mRNA and protein content of markers related to the ATI cell type (e.g., Tla, ICAM-1, connexin-43 and caveolin-1 and -2) [79], Whether or not this cell line can form functional tight junctions is currently under investigation in our laboratories. 

Anisotropy and nonuniformity are at least in part due to inhomogeneities in the distribution of gap junctions and the biophysical properties of the tissue are in fact influenced by the intercellular coupling. At least four features have to be considered. (1) Cardiac cells express different gap junction proteins (so-called connexins in the heart, connexin 40, connexin 43 and connexin 45 are most abundantly found for details see chapters 2 and 3). Channels formed by these connexins are different with regard to their biophysical properties. In various parts of the heart the content of each of these isoforms is different. 

Protein kinase Connexin Tissue Permeability g. Reference... 

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