High impact information on TRGJP

• After reduction with dithiothreitol this material was recovered in an elution volume identical to that of purified hJP and corresponding to a mol wt of ca. 3000 [1].
• This result was corroborated using HPLC purification to determine both amidated and glycine-extended forms of JP [2].
• Plasma IR-JP had circadian variations and responded to the metyrapone test in a manner strictly similar to that of ACTH and lipotropins (LPHs) [3].
• Normal male volunteers at 0800 h had plasma IR-JP values ranging from undetectable (< 6 pmol/L) to 28 pmol/L; all values were suppressed by the overnight 1 mg dexamethasone test [3].
• The other two variants were identified as human JP with a free cysteine residue and human JP dimer and accounted for 35% and 15%, respectively, of the total purified [4].

Biological context of TRGJP

• None of the three JP variants or their respective 1-20 amino-terminal fragments resulting from tryptic hydrolysis showed any ability to promote the secretion of dehydroepiandrosterone sulfate by cultured human fetal adrenal cells [4].
• The amino acid sequence of the bullfrog JP resembled the sequences of the JPs of Rana ridibunda (86% similarity) and Xenopus laevis (54% similarity), as deduced from the nucleotide sequences of their cDNAs [5].

Anatomical context of TRGJP

• We have examined the response of aldosterone to beta-endorphin (beta-End) and joining peptide (JP) and compared these with the response to ACTH using eight cell suspensions prepared from human adrenal glands [6].

Associations of TRGJP with chemical compounds

• The predominant form of human JP, accounting for about 50% of the total purified, was found to be conjugated to glutathione through the lone cysteine residue at position 9 [4].
• Furthermore, JP stimulated aldosterone biosynthesis (41 +/- 16 fmol/10(4) cells above basal; p < 0.05), only at the highest concentration used, 10(-6) M [6].
• JP (10(-10) M) inhibited ACTH-stimulated cortisol production so that the mean values fell to 5186 +/- 2588 and also inhibited DHEA production, from 240 +/- 48 to 180 +/- 33 pmol/10(6) cells [7].
• These results suggest that the relative production of androgen to cortisol is greater in response to beta-End and JP than in response to ACTH [7].
• NPP and ACTH, but not JP, enhanced LH release concentration-dependently [8].

Analytical, diagnostic and therapeutic context of TRGJP

• The joining peptide (JP) and the N-terminal peptide of proopiomelanocortin (NPP) were isolated from an acid-acetone extract of the distal lobe of the pituitary of the bullfrog, Rana catesbeiana, and purified by gel filtration and reverse-phase high performance liquid chromatography [5].
• Northern blot analysis showed that the probe derived from JP-GAL hybridized to a single 2.6 kb RNA [9].
• Labeling and immunoprecipitation experiments confirmed that three proopiomelanocortin (POMC)-derived peptides, the N-terminal peptide of POMC (NPP), joining peptide (JP) and adrenocorticotropic hormone (ACTH), were released by the bullfrog (Rana catesbeiana) anterior pituitary [8].

References