Proteins in the GRAS (GAI, RGA, SCR) family are known as major players in gibberellin (GA) signaling, which regulates various aspects of plant growth and development [1]. Mutation of the SCARECROW (SCR) gene results in a radial pattern defect, loss of a ground tissue layer, in the root. The PAT1 protein is involved in phytochrome A signal transduction [2]. A sequence, structure and evolutionary analysis showed that the GRAS family emerged in bacteria and belongs to the Rossmann-fold, AdoMET (SAM)-dependent methyltransferase superfamily [3]. All bacterial, and a subset of plant GRAS proteins, are predicted to be active and function as small-molecule methylases. Several plant GRAS proteins lack one or more AdoMet (SAM)-binding residues while preserving their substrate-binding residues. Although GRAS proteins are implicated to function as transcriptional factors, the above analysis suggests that they instead might either modify or bind small molecules [3].

1: The GRAS gene family in Arabidopsis: sequence characterization and basic expression analysis of the SCARECROW-LIKE genes. Pysh LD, Wysocka-Diller JW, Camilleri C, Bouchez D, Benfey PN; Plant J 1999;18:111-119. PMID:10341448

2: PAT1, a new member of the GRAS family, is involved in phytochrome A signal transduction. Bolle C, Koncz C, Chua NH; Genes Dev 2000;14:1269-1278. PMID:10817761

3: Bacterial GRAS domain proteins throw new light on gibberellic acid response mechanisms. Zhang D, Iyer LM, Aravind L; Bioinformatics. 2012;28:2407-2411. PMID:22829623

4: A Structure for Plant-Specific Transcription Factors: The GRAS Domain Revealed. Hofmann NR; Plant Cell. 2016;28:993-994. PMID:27095838

5: GRAS-domain transcription factors that regulate plant development. Hirsch S, Oldroyd GE; Plant Signal Behav. 2009;4:698-700. PMID:19820314