second type I K homology (KH) RNA-binding domain found in Arabidopsis thaliana RNA-binding KH domain-containing protein PEPPER and similar proteins
The family includes a group of plant RNA-binding KH domain-containing proteins, such as PEPPER, flowering locus K homology domain protein (FLK), RNA-binding KH domain-containing protein RCF3 and KH domain-containing protein HEN4. PEPPER regulates vegetative and gynoecium development. It acts as a positive regulator of the central floral repressor FLOWERING LOCUS C. In concert with HUA2, PEPPER antagonizes FLK by positively regulating FLC probably at transcriptional and post-transcriptional levels, and thus acts as a negative regulator of flowering. FLK, also called flowering locus KH domain protein, regulates positively flowering by repressing FLC expression and post-transcriptional modification. PEPPER and FLK contain three K-homology (KH) RNA-binding domains. RCF3, also called protein ENHANCED STRESS RESPONSE 1 (ESR1), or protein HIGH OSMOTIC STRESS GENE EXPRESSION 5 (HOS5), or protein REGULATOR OF CBF GENE EXPRESSION 3, or protein SHINY 1 (SHI1), acts as negative regulator of osmotic stress-induced gene expression. It is involved in the regulation of thermotolerance responses under heat stress. It functions as an upstream regulator of heat stress transcription factor (HSF) genes. HEN4, also called protein HUA ENHANCER 4, plays a role in floral reproductive organ identity in the third whorl and floral determinacy specification by specifically promoting the processing of AGAMOUS (AG) pre-mRNA. It functions in association with HUA1 and HUA2. RCF3 and HEN4 contain five KH RNA-binding domains. The model corresponds to the KH2 domain of PEPPER and FLK, as well as KH2 and KH4 domains of RCF3 and HEN4.