TABLE 3.

Host factors that restrict transposable element activity

Host defense machinery	Host factors / Function	Regulatory impact on Tf elements	Refs
Exosome	Pla1: canonical polyA polymerase	Elimination of transcripts via the exosome	(78)
	Red1: RNA surveillance factor		(96)
	Pab2: polyA binding protein
	Rrp6: exosome subunit
	Mtl1: component of Red1 associated MTREC complex		(79)
RNAi	Nrl1: splicing factor binding protein	Activation of RNAi response through recognition of cryptic introns	(79)
Under exosome deficiency or nutrient starvation	Clr4: histone methyltransferase	Activation of RNAi response through histone methylation	(78)
	Ago1: argonaute, RNA binding	Processing of mRNA into siRNAs and the formation of heterochromatin	(78)
	Dcr1: dicer, ribonuclease
	Rdr1: RNA-directed RNA polymerase
	Swi6: HP1 chromodomain protein	Heterochromatinization	(74)
Nucleosome deposition by histone chaperone complex HIRA	Hip1: hira histone chaperone	Inhibition of transcription through nucleosome deposition	(80,81)
	Hip3: HIRA interacting protein
	Slm9: HIRA protein
CENP-B proteins and associated factors	Abp1/Cbp1: CENP-B homolog	Inhibition of transcription	(86,87)
	Cbh1: CENP-B homolog	Restriction of homologous recombination
	Cbh2: CENP-B homolog	Recruitment of HDACs Clr3 and Clr6
	Clr3: histone deacetylase	Inhibition of transcription through histon hypoacetylation	(73,86,87)
	Clr6: histone deacetylase
	Set1: histone methyltransferase	Inhibition of sense and antisense transcription	(87)
	Ku70: Ku domain protein, DNA binding	Clustering into Tf-bodies	(88)
	Ku80: Ku domain protein, DNA binding