A. Proteins were immunoprecipitated with anti-CSNO antibody before, and two and 10 min after, cell treatment with calcium ionophore A23187; they were then immunoblotted with anti-eNOS. B. Proposed general schematic of nitrosonium (NO+) transfer following eNOS activation, based on our preliminary data. Arrows represent transnitrosylation (NO+ transfer between cysteines). Protein-scaffolding scheme adapted from Su, Kondrikov, and Block (ref. 25).