6H7E image
Entry Detail
PDB ID:
6H7E
Title:
GEF regulatory domain
Biological Source:
PDB Version:
Deposition Date:
2018-07-31
Release Date:
2020-02-19
Method Details:
Experimental Method:
Resolution:
2.30 Å
R-Value Free:
0.23
R-Value Work:
0.19
R-Value Observed:
0.19
Space Group:
I 1 2 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:cDNA FLJ56134, highly similar to Rap guanine nucleotide exchange factor 3
Chain IDs:A, B
Chain Length:270
Number of Molecules:2
Biological Source:Homo sapiens
Primary Citation
Membranes prime the RapGEF EPAC1 to transduce cAMP signaling.
Nat Commun 14 4157 4157 (2023)
PMID: 37438343 DOI: 10.1038/s41467-023-39894-4

Abstact

EPAC1, a cAMP-activated GEF for Rap GTPases, is a major transducer of cAMP signaling and a therapeutic target in cardiac diseases. The recent discovery that cAMP is compartmentalized in membrane-proximal nanodomains challenged the current model of EPAC1 activation in the cytosol. Here, we discover that anionic membranes are a major component of EPAC1 activation. We find that anionic membranes activate EPAC1 independently of cAMP, increase its affinity for cAMP by two orders of magnitude, and synergize with cAMP to yield maximal GEF activity. In the cell cytosol, where cAMP concentration is low, EPAC1 must thus be primed by membranes to bind cAMP. Examination of the cell-active chemical CE3F4 in this framework further reveals that it targets only fully activated EPAC1. Together, our findings reformulate previous concepts of cAMP signaling through EPAC proteins, with important implications for drug discovery.

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