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Gene Superfamily (gene + superfamily)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

Repressive domain of unliganded human estrogen receptor , associates with Hsc70

GENES TO CELLS, Issue 12 2005
Satoko Ogawa
Estrogen receptor (ER) is a hormone-inducible transcription factor as a member of the nuclear receptor gene superfamily. Unliganded ER is transcriptionally silent and capable of DNA binding; however, it is unable to suppress the basal activity of the target gene promoters, unlike non-steroid hormone receptors that associate with corepressors in the absence of their cognate ligands. To study the molecular basis of how unliganded human ER, is maintained silent in gene regulation upon the target gene promoters, we biochemically searched interactants for hER,, and identified heat shock protein 70 (Hsc70). Hsc70 appeared to associate with the N-terminal hormone binding E domain, that also turned out a transcriptionally repressive domain. Competitive association of Hsc70 with a best known coactivator p300 was observed. Thus, these findings suggest that Hsc70 associates with unliganded hER,, and thereby deters hER, from recruiting transcriptional coregulators, presumably as a component of chaperone complexes. [source]

Generation of a Snail1 (Snai1) conditional null allele

GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 1 2006
Stephen A. Murray
Abstract Members of the Snail gene superfamily, which encode zinc finger transcriptional repressors, play critical roles in the establishment of the vertebrate body plan. The Snail1 (Snai1) gene promotes epithelial,mesenchymal transitions during development and disease progression, and Snai1 null mouse embryos exhibit defects in gastrulation. However, the early embryonic lethality of Snai1 null embryos precludes the study of Snai1 function in other developmental contexts or diseases. To overcome this restriction, we generated a Snai1 conditional null allele by flanking the promoter and first two exons of the Snai1 gene with loxP sites. Cre-mediated deletion of the Snai1flox allele generates the Snai1del2 allele, which behaves genetically as a Snai1 null allele. This conditional null allele will enable investigation of Snai1 function in a variety of developmental and pathological contexts. genesis 44:7,11, 2006. © 2006 Wiley-Liss, Inc. [source]

Molecular cloning, characterization, expression pattern and cellular distribution of an ovarian lipophorin receptor in the cockroach, Leucophaea maderae

INSECT MOLECULAR BIOLOGY, Issue 3 2009
M. Tufail
Abstract A cDNA that encodes a lipophorin receptor (LpR) with a predicted structure similar to that of the low density lipoprotein receptor (LDLR) gene superfamily was cloned from ovaries of the cockroach, Leucophaea maderae (Lem) and characterized. This is the first LpR sequenced from the order Dictyoptera. The cDNA has a length of 3362 bp coding for an 888-residue mature protein with a predicted molecular mass of ~99.14 kDa and a pI value of 4.68. The deduced amino acid sequence showed that the LemLpR harbours eight ligand-binding repeats (LBRs) at the N-terminus similar to the other insect LpRs, and thus resembles vertebrate VLDLRs. In addition to eight tandemly arranged LBRs, the five-domain receptor contains an O -linked sugar region and the classic LDLR internalization signal, FDNPVY. Northern blot analysis revealed the presence of ~4.0 kb ovarian mRNA that was transcribed throughout oogenesis with its peak especially during late previtellogenic and vitellogenic periods (from days 3 to 11). LpR transcript(s) or homologues of LDLRs were also detected in the head, midgut, Malpighian tubules, muscles and in the fat body. RNA in situ hybridization and immunocytochemistry localized the LpR mRNA and protein to germ line-derived cells, the oocytes, and revealed that LpR gene transcription and translation starts very early during oocyte differentiation in the germarium. LpR protein was evenly distributed throughout the cytoplasm during previtellogenic periods of oogenesis. However, during vitellogenic stages, the receptor was accumulated mainly in the cortex of the oocyte. Immunoblot analysis probed an ovarian LpR protein of ~115 and 97 kDa under reducing and nonreducing conditions, respectively. The protein signal appeared on day 2, increased every day and was high during vitellogenic periods from day 4 to day 7. Southern blot analysis suggested the presence of a single copy of the LpR gene in the genome of Le. maderae. [source]

Odor discrimination by G protein-coupled olfactory receptors

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2002
Kazushige Touhara
Abstract The vertebrate olfactory system possesses a remarkable capacity to recognize and discriminate a variety of odorants by sending the coding information from peripheral olfactory sensory neurons in the olfactory epithelium to the olfactory bulb of the brain. The recognition of odorants appear to be mediated by a G protein-coupled receptor superfamily that consists of ,1% of total genes in vertebrates. Since the first discovery of the olfactory receptor gene superfamily in the rat, similar chemosensory receptors have been found in various species across different phyla. The functions of these receptors, however, had been uncharacterized until the recently successful functional expression and ligand screening of some olfactory receptors in various cell expression systems. The functional cloning of odorant receptors from single olfactory neurons allowed for the identification of multiple receptors that recognized a particular odorant of interest. Reconstitution of the odorant responses demonstrated that odorant receptors recognized various structurally-related odorant molecules with a specific molecular receptive range, and that odor discrimination is established based on a combinatorial receptor code model in which the identities of different odorants are encoded by a combination of odorant receptors. The receptor code for an odorant changes at different odorant concentrations, consistent with our experience that perceived quality of an odorant changes at different concentrations. The molecular bases of odor discrimination at the level of olfactory receptors appear to correlate well with the receptive field in the olfactory bulb where the input signal is further processed to create the specific odor maps. Microsc. Res. Tech. 58:135,141, 2002. © 2002 Wiley-Liss, Inc. [source]