The phosphorylation of the human estrogen receptor (ER) serine residue at position 118 is required for full activity of the ER activation function 1 (AF-1). This Ser118 is phosphorylated by mitogen-activated protein kinase (MAPK) in vitro and in cells treated with epidermal growth factor (EGF) and insulin-like growth factor (IGF) in vivo. Overexpression of MAPK kinase (MAPKK) or of the guanine nucleotide binding protein Ras, both of which activate MAPK, enhanced estrogen-induced and antiestrogen (tamoxifen)-induced transcriptional activity of wild-type ER, but not that of a mutant ER with an alanine in place of Ser118. Thus, the activity of the amino-terminal AF-1 of the ER is modulated by the phosphorylation of Ser118 through the Ras-MAPK cascade of the growth factor signaling pathways.

This paper describes a methodology for the rapid and highly selective detection of cocaine using a membrane protein channel combined with a DNA aptamer. The DNA aptamer recognizes the cocaine molecule with high selectivity. We successfully detected a low concentration of cocaine (300 ng/mL, the drug test cutoff limit) within 60 s using a biological nanopore embedded in a microchip.

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We describe here a novel class of cis-acting response elements for retinoid, vitamin D, and estrogen receptors which are widely spaced (10 to 200 bp) direct repeats (DRs) of the canonical 5-AGGTCA half-site recognition motif (DR10 to DR200). In contrast to the specificity previously observed with shortly spaced DRs (DR1 to DR5), the different receptors bind promiscuously to these novel elements to activate transcription in the presence of retinoic acid (RA), vitamin D, or estrogen. The greatest RA-dependent transactivation, seen with DR15, was similar to that observed with the canonical DR5. Both RA receptors and retinoid X receptors contribute to transactivation through widely spaced DR elements. With the estrogen receptor, DR15 was one-third as efficient as the classical palindromic response element. A further increase of spacer lengths progressively decreased the efficiency of transactivation. No transactivation was seen with widely spaced DRs when the thyroid and retinoid X receptors were coexpressed in the presence of their ligands. The progesterone receptor was also unable to transactivate through a DR10 element composed of its cognate binding motifs. These results considerably extend the response element repertoire of nuclear receptors and suggest the existence of promiscuous transcriptional regulation through common response elements, as well as the possibility of receptor ''cross-talk.''The members of the superfamily of nuclear receptors for steroid/thyroid hormones, vitamin D, and retinoic acids (RAs) are known to act as ligand-inducible transcriptional trans regulators by binding to cognate cis-acting regulatory elements referred to as ligand response elements (for reviews, see references 4, 8, 14, 18-20, 22, 35, 39, and 58). In general, ligand response elements are composed of distinct arrangements of the core motif 5Ј-PuG[G/T][T/A]CA-3Ј or closely related sequences, but some families of receptors exhibit distinct nucleotide preferences for a given position. For example, all steroid receptors require a G in position 3, while RA receptors (RARs), retinoid X receptors (RXRs), and thyroid hormone receptors (TRs) have a preference for G over T at this position. In contrast to the estrogen receptor (ER), which requires a T at position 4, the members of the glucocorticoid receptor family (glucocorticoid, mineralocorticoid, progesterone, and androgen receptors) bind only to motifs containing an A at this position. Alterations in other positions can also result in differential recognition by the various receptors. Mutational and crystal structure analyses have shown that three amino acids in the so-called P-box of the first zinc finger in the DNA-binding domain (DBD) are critically involved in the recognition of the core motif (10, 41, 43, 52, 55; for recent reviews, see references 18 and 19).In addition to receptor-specific differences in the recognition of the precise sequence of the core motif, specific binding of receptors also results from distinct arrangements of the repeated motifs. Steroid receptors ...

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