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Does the nuclear envelope contain two types of ligand‐gated Ca 2+ release channels?
Author(s) -
Guihard Gilles,
Proteau Sonia,
Rousseau Eric
Publication year - 1997
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/s0014-5793(97)00949-6
Subject(s) - ryanodine receptor , inner membrane , western blot , gene isoform , ligand (biochemistry) , biophysics , nuclear membrane , blot , cell nucleus , biology , biochemistry , chemistry , microbiology and biotechnology , receptor , membrane , nucleus , gene
The nuclear envelope is composed of two membranes deliminating a perinuclear space which displays functional properties similar to those of a Ca 2+ ‐storing compartment. ATP‐driven Ca 2+ uptake and InsP 3 ‐induced Ca 2+ release processes have been described in isolated nuclei. Recently, it was reported that cADP‐ribose and InsP 3 can trigger a nucleoplasmic Ca 2+ increase. It was hypothesized that the inner nuclear membrane possesses Ca 2+ channels that are regulated by ryanodine or InsP 3 . Radio‐ligand binding assays and Western blot experiments were performed in order to investigate their presence in sheep cardiac and rat liver nuclear envelopes. Ryanodine receptors (RyR) were not detected in liver nuclear envelopes by either binding assay or Western blot analysis. However, cardiac nuclear envelopes were found to retain a very low level of specific ryanodine binding, which was not detected on immuno‐blots obtained with three types of isoform‐specific RyR antibodies. In contrast, nuclear InsP 3 ‐binding sites were consistently detected in both cardiac and liver nuclear envelopes. Altogether, these results provide evidence for the major contributor InsP 3 ‐gated Ca 2+ channels in control of Ca 2+ release from the perinuclear space in liver and cardiac cells.