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Different roles of IP 4 and IP 3 in the signal pathway coupled to the TRH receptor in microinjected Xenopus oocytes
Author(s) -
Mahlmann Stefan,
Meyerhof Wolfgang,
Schwarz Jürgen R.
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)80026-2
Subject(s) - xenopus , receptor , chemistry , signal transduction , microbiology and biotechnology , microinjection , endocrinology , medicine , biology , biophysics , biochemistry , gene
Different effects of injected IP 4 and IP 3 , on membrane Cl − currents were observed in Xenopus oocytes previously microinjected with GH 3 , cell poly(A) + RNA. IP 3 induced a biphasic current response similar to that induced by TRH, whereas IP 4 regularly evoked a monophasic current response consisting of a prolonged inward current with superimposed oscillations. Membrane currents elicited by TRH were enhanced by prior injection of IP 4 , but not of IP 3 . In contrast to IP 3 ‐induced membrane currents, those evoked by IP 4 were independent of injection depth. Phorbol ester led to enhancement of the initial current after injection of IP 3 , whereas the current oscillations were greater following injection of IP 4 . The results indicate that, in Xenopus oocytes, IP 4 plays a role different from that of IP 3 within the signal transduction pathway initiated by ligand stimulation of a neuropeptide receptor.