Disease relevance of Smp2a

• The effect of Escherichia coli heat-stable (STA) enterotoxin on in vitro uptake of amino acids by small intestine of sucking rats during fluid accumulation [1].

High impact information on Smp2a

• Major isoenzymes of androsterone-sulphating sulphotransferase (AD-ST) were isolated from liver cytosols of weanling and young adult female rats and their isoelectric properties were compared [2].
• These results demonstrate that the pI variants of AD-ST are derived from the same precursor by post-translational modification or that they are products of closely related, but distinct, genes [2].
• The cDNA sequence (saGHF-1/Pit-1) encodes a protein of 371 amino acids (aa) containing a POU domain (aa 194-343) and a transactivation, STA domain (aa 1-128) [3].
• Addition of DEX to the media resulted in ST-40/41 and ST-60 mRNA expression at 20 and 35% of their initial values, respectively, in cultures maintained on matrigel and Chee's medium at 96 hr [4].
• Female GH secretory pattern appears to determine the high expression of ST-20/21 in postpubertal female rats, although male GH secretory pattern results in the low expression of ST-40/41 and ST-60 in mature male rats [5].

Biological context of Smp2a

• The cDNA, designated as ST-40, consisted of 1,015 base pairs which had an open reading frame of 852 base pairs encoding the entire rat STa subunit of 284 amino acids [6].
• The nucleotide base sequence of the ST-40 cDNA shared a strong homology of 94.4% with that of ST-20 cDNA encoding a hydroxysteroid ST which had been reported by us [6].
• The St-20 and ST-40 cDNAs encode rat liver hydroxysteroid sulfotransferases (HS-ST) that are 90% identical in amino acid sequence but exhibit different substrate preferences for dehydroepiandrosterone (DHEA), androsterone (AD), and cortisol (CS) [7].
• Because hormones have been implicated in the molecular regulation of the sulfotransferase multigene family, the effects of glucocorticoid and antiglucocorticoid hormones on rat hepatic hydroxysteroid sulfotransferase-a and aryl sulfotransferase IV gene expression were investigated in vivo and in primary rat hepatocyte culture [8].
• Based on the substrate specificities of the enzyme preparation obtained by anion exchange chromatography and 3'-phosphoadenosine 5'-phosphate (PAP)-agarose affinity chromatography, AD-ST was supposed to be among isoenzymes of hydroxysteroid STs [9].

Anatomical context of Smp2a

• On the other hand, AD-ST is evident in the hepatocytes proximal to the portal triad in males, while in females it is synthesized and localized in all the hepatocytes [10].
• The lectins MPA and STA may be, therefore, used as the specific markers of malignancy in rat thyroid carcinogenesis [11].

Associations of Smp2a with chemical compounds

• Some chimeric enzymes were enzymatically active for all three substrates, and some displayed reduced or lost CS-ST activity, with retention of DHEA- and AD-ST activities [7].
• Rat hepatic hydroxysteroid sulfotransferase with sulfoconjugates androsterone (androsterone-sulfating sulfotransferase) is an oligomer consisting of several subunits with distinct pI values but with the same molecular mass (pI variants) [12].
• Furthermore, selective decrease in CS-ST activity was also observed in the alanine mutant at lysine 254 or at asparagine 255 of the ST-40 enzyme [13].
• The substitution of alanine or lysine for the histidine at position 98 in the ST-40 enzyme resulted in a loss of ST activities toward dehydroepiandrosterone (DHEA), androsterone (AD) and cortisol (CS) [13].
• In the ST-40 enzyme, the mutation at histidine 256 into alanine markedly reduced CS-ST activity, but DHEA-ST activity was not changed [13].

Regulatory relationships of Smp2a

• It has been previously reported that in vivo treatment with CYP1A1 inducer 3-methylcholanthrene (3-MC) suppresses rat hepatic HST-a mRNA expression in a dose-dependent manner [14].

Other interactions of Smp2a

• Dexamethasone produced maximal increases in aryl sulfotransferase IV and tyrosine aminotransferase mRNA levels when added to culture medium at a concentration of 10(-7) M, whereas hydroxysteroid sulfotransferase-a mRNA levels continued to increase through a dexamethasone concentration of 10(-5) M [8].

Analytical, diagnostic and therapeutic context of Smp2a

• The AD-ST activities eluted in fractions I and II were separately purified by 3'-phosphoadenosine 5'-phosphate-agarose affinity chromatography at both ages [2].
• In contrast, hypophysectomy elevated ST-40/41 and ST-60 expression in males [5].
• Next we determined the genetic loci of ST-40 and ST-20 by fluorescence in situ hybridization [15].
• Northern blot and slot blot analyses showed that rat hepatic hydroxysteroid sulfotransferase-a mRNA expression was responsive to age- and gender-related signals [16].
• Northern blot and reverse transcriptase polymerase chain reaction analyses demonstrated that hydroxysteroid sulfotransferase-a mRNA was expressed to a greater extent in female rat liver than in lung or kidney tissue [16].

References