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ECB-ART-46808
Biochim Biophys Acta Mol Cell Res 2019 Jul 01;18667:1180-1188. doi: 10.1016/j.bbamcr.2018.11.017.
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5-Azido-8-ethynyl-NAADP: A bifunctional, clickable photoaffinity probe for the identification of NAADP receptors.

Gunaratne GS , Su P , Marchant JS , Slama JT , Walseth TF .


Abstract
Nicotinic acid adenine dinucleotide phosphate is an evolutionarily conserved second messenger, which mobilizes Ca2+ from acidic stores. The molecular identity of the NAADP receptor has yet to be defined. In pursuit of isolating and identifying NAADP-binding proteins, we synthesized and characterized a bifunctional probe that incorporates both a photoactivatable crosslinking azido moiety at the 5-position of the nicotinic ring and a ''clickable'' ethynyl moiety to the 8-adenosyl position in NAADP. Microinjection of this 5N3-8-ethynyl-NAADP into cultured U2OS cells induced robust Ca2+ responses. Higher concentrations of 5N3-8-ethynyl were required to elicit Ca2+ release or displace 32P-NAADP in radioligand binding experiments in sea urchin egg homogenates. In human cell extracts, incubation of 32P-5N3-8-ethynyl-NAADP followed by UV irradiation resulted in selective labeling of 23 kDa and 35 kDa proteins and photolabeling of these proteins was prevented when incubated in the presence of unlabeled NAADP. Compared to the monofunctional 32P-5N3-NAADP, the clickable 32P-5N3-8-ethynyl-NAADP demonstrated less labeling of the 23 kDa and 35 kDa proteins (~3-fold) but provided an opportunity for further enrichment through the ''clickable'' ethynyl moiety. No proteins were specifically labeled by 32P-5N3-8-ethynyl-NAADP in sea urchin egg homogenate. These experiments demonstrate that 5N3-8-ethynyl-NAADP is biologically active and selectively labels putative NAADP-binding proteins in mammalian systems, evidencing a ''bifunctional'' probe with utility for isolating NAADP-binding proteins.

PubMed ID: 30521871
PMC ID: PMC8101546
Article link: Biochim Biophys Acta Mol Cell Res
Grant support: [+]

Genes referenced: LOC100887844 LOC115919910 LOC576539

References [+] :
Aarhus, Activation and inactivation of Ca2+ release by NAADP+. 1996, Pubmed, Echinobase