InterPro domain: IPR016818

This entry includes animal NOSIP (nitric oxide synthase-interacting protein) and plant CSU1. They are ubiquitin E3 ligases [ 1 , 2 ]. Human NOSIP negatively regulates nitric oxide production by inducing NOS1 and NOS3 translocation to actin cytoskeleton and inhibiting their enzymatic activity [ 3 , 4 , 5 ].

Arabidopsis CSU1 plays a important role in maintaining COP1 homeostasis by targeting COP1 for ubiquitination and degradation in dark-grown seedlings [ 6 ].

1. The ubiquitin E3 ligase NOSIP modulates protein phosphatase 2A activity in craniofacial development. PLoS ONE 9, e116150
2. The RING-Finger E3 Ubiquitin Ligase COP1 SUPPRESSOR1 Negatively Regulates COP1 Abundance in Maintaining COP1 Homeostasis in Dark-Grown Arabidopsis Seedlings. Plant Cell 26, 1981-1991
3. NOSIP, a novel modulator of endothelial nitric oxide synthase activity. FASEB J. 15, 79-89
4. Nitric oxide synthase (NOS)-interacting protein interacts with neuronal NOS and regulates its distribution and activity. J. Neurosci. 24, 10454-65
5. Cell cycle-regulated inactivation of endothelial NO synthase through NOSIP-dependent targeting to the cytoskeleton. Mol. Cell. Biol. 25, 8251-8