No end to protein modification

A new biological signalling molecule is described online this week in Nature Chemical Biology. Nitric oxide, or NO, is a common messenger in biological systems and produces a variety of physiological responses, but the precise signalling pathways involved have so far remained unclear.

Takaaki Akaike and colleagues now show that cellular NO production produces a ‘nitrated’ second messenger called 8-nitro-cGMP, which bears a chemical resemblance to a known signalling molecule, cyclic GMP (cGMP). Because of this similarity, 8-nitro-cGMP is a good mimic and can activate several of cGMP’s standard signalling pathways. However 8-nitro-cGMP has a number of additional functions including the ability to tag proteins with a cGMP tag. The discovery of these new pathways and modifications provides new insights into NO physiology and pathological responses.