60 YEARS OF POMC: Lipotropin and beta-endorphin: a perspective
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Figure 1
Alignment of peptides isolated from porcine pituitary in the amino acid sequence of lipotropin (LPH). The C-fragment of lipotropin (β-endorphin) corresponds to lipotropin residues 61–91, the Cʹ-fragment to lipotropin residues 61–87, and β-MSH to residues 41–58. Reprinted from Biochemical and Biophysical Research Communications, 69, Bradbury AF, Smyth DG & Snell CR, Lipotropin: Precursor to two biologically active peptides, 950–956. Copyright (1976), with permission from Elsevier.
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Figure 2
Rate of release of N-terminal tyrosine from β-endorphin and structurally related synthetic peptides. The peptides (0.34 mM) were incubated at 37˚C with aminopeptidase M (lower figure, 0.02 mg/mL) or with a preparation of an aminopeptidase from rat brain (upper figure) in 0.1 M ammonium bicarbonate at pH 7.4. dl-Norleucine was included as an internal standard. At intervals, aliquots of the solutions were added to 1 mL of 0.2 M citrate at pH 2.2 and the liberated tyrosine was determined by amino acid analysis. Reprinted from Biochemical and Biophysical Research Communications, 76, Austin BM & Smyth DG, The NH2-terminus of C-Fragment is resistant to the action of aminopeptidases, 476–482. Copyright (1977), with permission from Elsevier.
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Figure 3
(Plate 1) Localisation of peptides related to β-endorphin in regions of rat brain by immunofluorescence scanning. (A) β-endorphin synthesising cell bodies and beaded fibres are seen in the median eminence and arcuate nucleus; cell bodies with dark unstained nuclei are surrounded by positively stained cytoplasm. (B) Numerous beaded axons typical of the region of the thalamus and midbrain. (C) Dense fibres and terminals in the amygdaloid nucleus. (D) Relatively sparse but highly organised fibres and axon throughout the brainstem are visible. (Plate 2) Different forms of β-endorphin fluorescence in rat hypothalamus. (A’) Cell bodies synthesising β-endorphin and β-endorphin containing fibres in the region of the arcuate nucleus. (B’) Cell bodies and fibres ventromedial to the third ventricle. (C’) Dense fluorescence in the form of axons and fibres along the length of the wall of the third ventricle. (D’) Long beaded axons extending dorsolaterally from the ventricle towards the thalamus. Reproduced, with permission, from Zakarian S & Smyth DG, 1982, Biochemical Journal, 202, 561–571. Copyright the Biochemical Society.
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Figure 4
Ion-exchange chromatography of β-endorphin-related peptides extracted from the regions of rat brain. The β-endorphin-containing fractions obtained by gel exclusion were resolved by SP Sephadex C-25 chromatography (Sigma-Aldrich). The peptides were detected by RIA with a β-endorphin antiserum. The elution positions of the radio-labelled reference peptides (α-N-acetyl β-endorphin(1–27), β-endorphin(1–27), α-N-acetyl β-endorphin(1–31) and β-endorphin(1–31) are indicated from left to right by the arrows. α-N-acetyl des-histidine β-endorphin(1–27) and des-histidine β-endorphin(1–27) are not indicated by markers. Reproduced, with permission, from Zakarian S & Smyth DG, 1982, Biochemical Journal, 202, 561–571. Copyright the Biochemical Society.
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Figure 5
Localisation of peptides related to β-endorphin (A) in the anterior pituitary and (B) in the pars intermedia of the rat by immunofluorescence scanning. Serial sections of perfused and fixed brain from Lewis rats were stained with the antibody to β-endorphin. Reproduced, with permission, from Zakarian S & Smyth DG, 1982, Biochemical Journal, 202, 561–571. Copyright the Biochemical Society.
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Figure 6
Ion-exchange chromatography of β-endorphin-related peptides extracted from the regions of rat pituitary. The β-endorphin-containing fractions obtained by gel exclusion were resolved by exchange chromatography: (A) anterior pituitary and (B) pars intermedia. The arrows from L to R indicate the elution positions of the I125-labelled peptides, α-N-acetyl β-endorphin(1–27), β-endorphin(1–27), α-N-acetyl β-endorphin(1–31) and β-endorphin(1–31). Reproduced, with permission, from Zakarian S & Smyth DG, 1982, Biochemical Journal, 202, 561–571. Copyright the Biochemical Society.
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Figure 7
Resolution by ion-exchange chromatography of acetyl α-MSH and des-acetyl α-MSH extracted from the pars intermedia of Xenopus laevis adapted to black or white backgrounds. The peptides purified by gel exclusion on Sephadex G-50 and ion-exchange chromatography on SP Sephadex C-25 were located by RIA with MSH antibody after (A) 2 weeks adaptation to a daylight background and (B and C) after 2 and 4 weeks adaptation to a black background. Reproduced, with permission, from Maruthainar et al. (1992).
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