SRR1 proteins are signalling proteins involved in regulating the circadian clock in Arabidopsis[1]. This presumed domain has a Rossmann-like fold and structural models suggest it may have a methyltransferase function.

1: The Arabidopsis SRR1 gene mediates phyB signaling and is required for normal circadian clock function. Staiger D, Allenbach L, Salathia N, Fiechter V, Davis SJ, Millar AJ, Chory J, Fankhauser C; Genes Dev 2003;17:256-268. PMID:12533513