The proteins such as DRM2, ARGONAUTE 4 (AGO4) and Pol V strengthened siRNA biogenesis but researchers have no clear cut idea for the mechanism. siRNA refers to small interfering RNA, which have a lot of essential roles in biology involving the interference in the expression of a specific gene.
The enzymes Pol II, Pol V and Pol IV have an important relationship with each other but the relationship is still not much clear. Pol refers to Polymerase enzymes, which are involved in the production of RNA.
Researchers have found that DRD1 (DEFECTIVE IN RNA-DIRECTED DNA METHYLATION 1) and DMS3 are essential for NRPE1-chromatin linkage and for accumulation of IGN transcripts. However, work has still to be done on probable mechanism of targeting of these components. DRD1 is a putative chromatin-remodeling factor. DMS3 refers to DEFECTIVE IN MERISTEM SILENCING 3, which is a component in RNA-directed DNA methylation (RdDM) having similarity to structural maintenance of chromosome (SMC) proteins. NRPE 1 refers to NUCLEAR RNA POLYMERASE E1.
The mechanism for silencing in sperm cells as a result of siRNA in the vegetative nucleus that travelled to sperm cells is also not known.
The mechanism of LSH1 functioning in DNA methylation is also not so much clear.
Law, J. A., & Jacobsen, S. E. (2010). Establishing, maintaining and modifying DNA methylation patterns in plants and animals. Nature Reviews Genetics, 11, 204-220.