Chromogranin A-like proteins in the secretory granules of a protozoan, Paramecium tetraurelia

J. B. Peterson, D. L. Nelson, E. Ling, R. H. Angeletti

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


The ciliate protozoan Paramecium tetraurelia produces secretory granules (trichocysts) which release needle-like structures composed of small, acidic proteins. Using antibodies against isolated chromogranin A (CGA) and against trichocyst proteins, we found cross-reactive proteins in chromaffin granules and trichocysts. Four independently derived sera against isolated CGA stained bands of the M(r) 15,000-25,000 family of trichocyst proteins on immunoblots. A positive response was also obtained with antiserum against chemically synthesized peptides (PL26 and GE25) corresponding to defined regions of the CGA amino acid sequence. In extracts of whole Paramecium, larger proteins (M(r) 53,000 and 49,000) also reacted with antibodies against CGA and the related synthetic peptides. These larger proteins may represent unprocessed precursors to the smaller proteins of mature trichocysts. Antiserum to trichocysts recognized CGA in chromaffin granule lysates. Further evidence of a Paramecium protein related to CGA was provided by hybridization of Paramecium mRNA with cloned cDNA for bovine CGA. Our results suggest striking conservation in evolution of CGA-like proteins that may play some role, as yet unknown, in secretion.

Original languageEnglish (US)
Pages (from-to)17264-17267
Number of pages4
JournalJournal of Biological Chemistry
Issue number36
StatePublished - 1987
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


Dive into the research topics of 'Chromogranin A-like proteins in the secretory granules of a protozoan, Paramecium tetraurelia'. Together they form a unique fingerprint.

Cite this