A reevaluation of dual-targeting of proteins to mitochondria and chloroplasts

► Over 100 proteins are now known to be dual-targeted to mitochondria and plastids. ► Dual-targeted proteins are biased towards soluble proteins implicated in DNA and RNA metabolism and/or translation. ► Targeting specificity for both organelles tends to physically overlap within targeting sequences. ► The dual-targeted state tends to persist over evolutionary timescales, implying a selective advantage.