Sequence and tissue distribution of a second protein of hepatic gap junctions, Cx26, as deduced from its cDNA.

Abstract

Abstract. While a number of different gap junction proteins have now been identified, hepatic gap junctions are unique in being the first demonstrated case where two homologous, but distinct, proteins (28,000 and 21,000 Mr) are found within a single gap junctional plaque

Establishment and characterization of differentiated, nontransformed hepatocyte cell lines derived from mice transgenic for transforming growth factor alpha.

“…The connexins are a family of gap-junction proteins which are differentially expressed in tissue-specific patterns. Cx 26 and Cx 32 are the only types known to exist in hepatocytes, whereas Cx 43 is found in bile ductules and dedifferentiated liver cell lines (6,26,27,33). At 4 months in culture, both AML lines synthesized the 2.4-kb Cx 26 and 1.8-kb Cx 32 transcripts at levels comparable to that of 1-day cultured hepatocytes (Fig.…”

“…Northern blot analysis was performed on total RNA extracted from cultured cells at 70% confluence (12,21). Filters were hybridized at 50°C [for the connexin (Cx) 32 probe] or 42°C (all other probes) with the following 32P-labeled probes: a 240-bp Pst I cDNA fragment recognizing human and mouse TGFa mRNA; a 2.4-kb human EGFR cDNA insert from pE7 (22); the mouse albumin cDNA insert from pmalb2 (23); a 0.5-kb Bgl I-BamHI a-fetoprotein (AFP) cDNA fragment from pBAF700 (24); the mouse a1-antitrypsin (AlAT) insert in pLivS3 and transferrin insert in pLivS6 (from H. Isom, Pennsylvania State University College of Medicine) (25); the rat Cx 26 and 32 cDNAs in pSP42T and pGEM-3, respectively (from D. Paul, Harvard Medical School) (6,26); the rat Cx 43 insert in pBS (from E. Beyer, Washington University School of Medicine) (27); and a 1.2-kb rat glyceraldehyde-3-phosphate dehydrogenase cDNA from pRLC-GAP (from J. Tso, X.-H. Sun, and R. Wu, Cornell University). For multiple probings, filters were stripped in 1% (vol/vol) glycerol at 80°C for 3 min before rehybridization.…”

2-acetylaminofluorene dose-dependent differentiation of rat oval cells into hepatocytes: Confocal and electron microscopic studies

“…Connexin 32 is expressed on hepatocytes, and connexin 43 is expressed on the biliary epithelial cells in the normal rat liver. 39 Zhang and Thorgeirsson 40 reported that the mRNA for connexin 43 is expressed in the oval cells and connexin 32 in the small hepatocytes of the foci. Here we confirm this observation at the protein level.…”

Expression of gap junction proteins Cx26, Cx31.1, Cx37, and Cx43 in developing and mature rat epidermis

“…Molecular studies have identified a large family of connexin genes encoding gap junction channel proteins. To date, 12 connexin genes have been cloned and characterized from rodents (Kumar and Gilula, 1986;Paul, 1986;Beyer et al, 1987;Zhang and Nicholson, 1989;Paul et al, 1991;Hoh et al, 1991;Willecke et al, 1991;Haefliger et al, 1992;Hennemann et al, 1992a,b;White et al, 1992), and many of their homologs have been cloned from Xenopus (Ebi-0 1994 WILEY-LISS, INC. hara et al, 1989;Gimlich et al, 1988), chick (Beyer, 19901, and human (Kumar and Gilula, 1986;Fishman et al, 1990). The different connexin proteins often display characteristic differences in their sensitivity to voltage, changes in pH, phosphorylation, and pharmacological reagents, thus permitting the formation of gap junctions with varied physiological properties that are likely to be required by different tissues.…”