Science and Mathematics Faculty Publications

Title

PACAP-38 Is a Chemorepellent and an Agonist for the Lysozyme Receptor in Tetrahymena thermophila

Document Type

Article

Publication Date

1-18-2000

Journal Title

Journal of Comparative Physiology A

Volume

186

Issue

1

First Page

39

Last Page

43

Abstract

Pituitary adenylate cyclase activating peptide (PACAP-38) is a peptide hormone which functions in many mammalian systems, including the nervous and digestive systems. Using in vivo behavioral studies, we have found that this hormone functions as a chemorepellent in Tetrahymena thermophila with an EC50 of 10 nM. Cells previously adapted to PACAP-38 were found to be adapted to lysozyme, and vice versa. Furthermore, the in vivo behavioral activity of PACAP-38 was blocked by addition of the anti-lysozyme receptor antibody, 5545. Chemorepellent activity of PACAP-38 was also inhibited by the addition of neomycin sulfate (inhibition constant Ki=0.080 μmol · l−1), a competitive inhibitor of lysozyme binding to its receptor. PACAP-38 is a more potent and specific agonist for the lysozyme receptor than either intact lysozyme or CB2, a 24-amino acid fragment of lysozyme.

Keywords

Chemorepellent, PACAP-38, Tetrahymena, Chemosensory transduction, Behavioral adaptation

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