Component of the PAF1 complex (PAF1C) which is involved in histone modifications such as methylation on histone H3 'Lys-4' (H3K4me3) (PubMed:20363855). Involved in regulation of flowering time. Required for the expression of the flowering repressors FLC and MADS-box genes of the MAF family. Required for histone H3 trimethylation on 'Lys-4' (H3K4me3) at the FLC locus (PubMed:20363855, PubMed:20463090). Prevents trimethylation on 'Lys-27' (H3K27me3) at the same locus (PubMed:20363855). Component of the nuclear PAF1 complex (PAF1C), which consists of VIP2/ELF7/PAF1, VIP3/SKI8/WDR61, VIP4/LEO1, VIP5/RTF1, VIP6/ELF8/CTR9 and CDC73. Expressed in root tips, shoot apex, young leaves and flowers, especially in stamen filaments and carpels. Early flowering. Belongs to the CDC73 family.