Editing Cell nucleus (section)

====PIKA and PTF domains====
PIKA domains, or polymorphic interphase karyosomal associations, were first described in microscopy studies in 1991. Their function remains unclear, though they were not thought to be associated with active DNA replication, transcription, or RNA processing.<ref name="Saunders">{{cite journal | vauthors = Saunders WS, Cooke CA, Earnshaw WC | title = Compartmentalization within the nucleus: discovery of a novel subnuclear region | journal = The Journal of Cell Biology | volume = 115 | issue = 4 | pages = 919–31 | date = November 1991 | pmid = 1955462 | pmc = 2289954 | doi = 10.1083/jcb.115.4.919 | department = Primary }}</ref> They have been found to often associate with discrete domains defined by dense localization of the transcription factor PTF, which promotes transcription of [[small nuclear RNA]] (snRNA).<ref name="Pombo">{{cite journal | vauthors = Pombo A, Cuello P, Schul W, Yoon JB, Roeder RG, Cook PR, Murphy S | title = Regional and temporal specialization in the nucleus: a transcriptionally-active nuclear domain rich in PTF, Oct1 and PIKA antigens associates with specific chromosomes early in the cell cycle | journal = The EMBO Journal | volume = 17 | issue = 6 | pages = 1768–78 | date = March 1998 | pmid = 9501098 | pmc = 1170524 | doi = 10.1093/emboj/17.6.1768 | department = Primary }}</ref>