ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract: The distribution of five major products of proenkephalin B [dynorphin1–17, dynorphin B, dynorphin1–8, α-neo-endorphin and β-neo-endorphin] was studied in regions of rat brain and pituitary. The distribution pattern of immunoreactive (ir) dynorphin B (= rimorphin) was found to be similar to that of irdynorphin1–17, with the highest concentrations being present in the posterior pituitary and the hypothalamus. HPLC and gel filtration showed the tridecapeptide dynorphin B to be the predominant immunoreactive species recognized by dynorphin B antibodies in all brain areas and in the posterior pituitary. In addition, two putative common precursor forms of dynorphin B and dynorphin1–17 with apparent molecular weights of 3,200 and 6,000 were detected in brain and the posterior pituitary. The 3,200 dalton species coeluted with dynorphin1–32 on HPLC. In contrast with all other tissues, anterior pituitary ir-dynorphin B and ir-dynorphin1–17 consisted exclusively of the 6,000 dalton species. Concentrations of dynorphin1–8 were several times higher than those of dynorphin1–17 in striatum, thalamus, and midbrain while posterior pituitary, hypothalamus, pons/medulla, and cortex contained roughly equal concentrations of these two opioid peptides. No dynorphin1–17 was detected in the anterior pituitary. Concentrations of β-neo-endorphin were similar to those of α-neo-endorphin in the posterior pituitary. In contrast, in all brain tissues α-neo-endorphin was found to be the predominant peptide, with tissue levels in striatum and thalamus almost 20 times higher than those of β-neo-endorphin. These findings indicate that differential proteolytic processing of proenkephalin B occurs within different regions of brain and pituitary. Moreover, evidence is provided that, in addition to the paired basic amino acids -Lys-Arg- as the “typical” cleavage site for peptide hormone precursors, other cleavage signals also seem to exist for the processing of proenkephalin B.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1984.tb02698.x
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