 Most proteins , ribosomal subunits , and some DNAs are transported through the pore complexes in a process mediated by a family of transport factors known as karyopherins . Those karyopherins that mediate movement into the nucleus are also called importins , whereas those that mediate movement out of the nucleus are called exportins . Most karyopherins interact directly with their cargo , although some use adaptor proteins . Steroid hormones such as cortisol and aldosterone , as well as other small lipid @-@ soluble molecules involved in intercellular signaling , can diffuse through the cell membrane and into the cytoplasm , where they bind nuclear receptor proteins that are trafficked into the nucleus . There they serve as transcription factors when bound to their ligand ; in the absence of ligand , many such receptors function as histone deacetylases that repress gene expression . 
 Most proteins , ribosomal subunits , and some DNAs are transported through the pore complexes in a process mediated by a family of transport factors known as karyopherins . Those karyopherins that mediate movement into the nucleus are also called importins , whereas those <a href='null_relcl' title='1'><mark>that</mark></a>mediate movement out of the nucleus are called exportins . Most karyopherins interact directly with their cargo , although some use adaptor proteins . Steroid hormones such as cortisol and aldosterone , as well as other small lipid @-@ soluble molecules involved in intercellular signaling , can diffuse through the cell membrane and into the cytoplasm , where they bind nuclear receptor proteins <a href='null_relcl' title='2'><mark>that</mark></a>are trafficked into the nucleus . There they serve as transcription factors when bound to their ligand ; in the absence of ligand , many such receptors function as histone deacetylases <a href='null_relcl' title='3'><mark>that</mark></a>repress gene expression . 
Most proteins , ribosomal subunits , and some DNAs r transported through the pore complexes in a process mediated by a fam of transport factors known as karyopherins . Those karyopherins dat mediate movement into the nucleus are also called importins , whereas those mediate movement outt of the nucleus are called exportins . Most karyopherins interact directly with their cargo , although sum use adaptor proteins . Steroid hormones such as cortisol and aldosterone , as well as other small lipid @-@ soluble molecules involved in intercellular signaling , can diffuse thru da cell membrane and into the cytoplasm , where they bind nuclear receptor proteins arrrafficked into the nucleus . There they serve as transcription factors when bound to their ligand ; in tdaabsence of ligand , many such receptors function as histone deacetylases repress gene expression .