Chromogranin A: Osmotically active fragments and their susceptibility to proteolysis during lysis of the bovine chromaffin granules

K. B. Helle, R. K. Reed, M. Ehrhart, D. Aunis, R. Hogue Angeletti

Research output: Contribution to journalArticle

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Abstract

Osmotically active fragments of chromogranin A (Chr A) were studied in lysates from bovine chromaffin granules (CG) disrupted in the presence or absence of inhibitors of endogenous proteolytic activities. The effects of various methods of lysis were examined by micro-osmometry, PAGE-SDS electrophoretic techniques and immunoblots with polyclonal anti-Chr A sera. Osmotically active 'small' Chr A fragments (below 30 kDa) were conspicuous in lysates containing cocktails of leupeptin, pepstatin A, pHMB, PMSF and aprotinin. The osmotically inactive native Chr A in the 68-100 kDa range and the osmotically active fragments below 47 kDa were degraded in lysates at neutral or acid pH in the absence of inhibitors. However, degradation of the native Chr A and intermediates below 47 kDa could be prevented by extraction directly from intact CG, notably in cold or boiling distilled water. On the other hand, the main product after large-scale extraction of CG in 1 M acetic acid (pH 1.9, 100°C) was a novel, osmotically active fragment (22 kDa), immunostaining only for the N-terminal sequence (Chr A1-40). The heat-stable fraction (M(r,n))̄ 23 kDa) exhibited concentration-independent colloid osmotic pressures even in the absence of phosphate, a property which may distinguish this N-terminal-containing fragment from the larger intermediates, probably containing the pancreastatin sequence, and other regions at the C-terminal side of the prohormone molecule. The functional roles of these osmotically active intermediates in the processing of Chr A are not yet known.

Original languageEnglish (US)
Pages (from-to)565-574
Number of pages10
JournalActa Physiologica Scandinavica
Volume138
Issue number4
StatePublished - 1990
Externally publishedYes

Fingerprint

Chromaffin Granules
Chromogranin A
Proteolysis
Osmometry
Aprotinin
Osmotic Pressure
Colloids
Acetic Acid
Polyacrylamide Gel Electrophoresis
Hot Temperature
Phosphates
Acids
Water
Serum

Keywords

  • Chr A
  • chromogranins
  • immunoactive fragments
  • limited proteolysis
  • osmotic behaviour

ASJC Scopus subject areas

  • Physiology

Cite this

Chromogranin A : Osmotically active fragments and their susceptibility to proteolysis during lysis of the bovine chromaffin granules. / Helle, K. B.; Reed, R. K.; Ehrhart, M.; Aunis, D.; Hogue Angeletti, R.

In: Acta Physiologica Scandinavica, Vol. 138, No. 4, 1990, p. 565-574.

Research output: Contribution to journalArticle

Helle, K. B. ; Reed, R. K. ; Ehrhart, M. ; Aunis, D. ; Hogue Angeletti, R. / Chromogranin A : Osmotically active fragments and their susceptibility to proteolysis during lysis of the bovine chromaffin granules. In: Acta Physiologica Scandinavica. 1990 ; Vol. 138, No. 4. pp. 565-574.
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