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Gel-filtration chromatography of an acid-extract of a phaeochromocytoma, under dissociating conditions, revealed 4 peaks of immunoreactive somatostatin (IRS) of approx. 8-10 kilodaltons (K), 6K, 3.5K and 1.6K as detected by an antiserum (R9) directed against the central region of tetradecapeptide somatostatin (S14). The 3.5K and 1.6K forms of IRS co-eluted with synthetic cyclic S28 and S14 respectively on reversed phase HPLC. Using another radioimmunoassay for the 1-14 sequence of S28 (N-peptide) a peak of immunoreactive N-peptide (IRN) with a molecular weight of approx. 4500 was observed. The antiserum (N3) used in the N-peptide assay was raised against N-Tyr N-peptide and cross-reacts less than 5% with synthetic S28. Two peaks were further characterised by partial tryptic digestion and gel-filtration chromatography. The 3.5K IRS peak was partially converted to a 1.6K IRS form together with an approximately equimolar amount of IRN with apparent molecular weight of 2500. This 2.5K IRN co-eluted both with N-Tyr N-peptide and with the IRN generated by tryptic digestion of synthetic cyclic S28. No IRN peak of this size was observed in the original extract. Tryptic digestion of the 6K IRS peak generated 3.5K and 1.6K IRS and 2.5K IRN. These results suggested that (1) this human phaeochromocytoma contains IRS very similar to the known structure of ovine and porcine S28 and S14. (2) The 6K IRS is composed of an unknown peptide sequence attached via trypsin-susceptible bond to the N-terminus of S28. (3) In this tumour S14 is being generated directly from 6K IRS and not via S28.
P Wu, and
E Penman, and
D H Coy, and
L H Rees
February 1984,
The Journal of neuroscience : the official journal of the Society for Neuroscience,
P Wu, and
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D H Coy, and
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May 1989,
BMJ (Clinical research ed.),
P Wu, and
E Penman, and
D H Coy, and
L H Rees
December 1983,
The Journal of clinical investigation,
P Wu, and
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D H Coy, and
L H Rees
June 1981,
Brain research,
P Wu, and
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May 1985,
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P Wu, and
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D H Coy, and
L H Rees
July 1982,
Endocrinology,
P Wu, and
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L H Rees
November 1987,
Hormone and metabolic research = Hormon- und Stoffwechselforschung = Hormones et metabolisme,
P Wu, and
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D H Coy, and
L H Rees
August 1996,
Tissue & cell,
P Wu, and
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L H Rees
May 1985,
Endocrinology,
