Immunolocalization of S-nitrosoglutathione, S-nitrosoglutathione reductase and tyrosine nitration in pea leaf organelles

S-Nitrosoglutathione (GSNO) is a nitrosothiol which plays a major role in the metabolism of NO in higher plants mediating signaling processes. Protein tyrosine nitration (NO₂–Tyr) is a post-translational modification which contributes to protein regulation. The subcellular localization of GSNO, S-nitrosoglutathione reductase (GSNOR), an enzyme which catalyzes its decomposition and protein tyrosine nitration was studied in pea (Pisum sativum L.) leaf plants with the aid of the electron microscopy immunogold-labeling technique. Our findings show that GSNO, GSNOR and nitrated proteins are present in the different subcellular compartments of leaf cells which include chloroplasts, cytosol, mitochondria, and peroxisomes. Given that pea peroxisomes are one of the cell compartments where nitric oxide (NO) has been thoroughly studied, our results provide additional insights into the metabolism of NO in this organelle where NO and GSNO could function as signal molecules in cross talk between the different cell compartments.