A comparison of the activity, sequence specificity, and CRM1-dependence of different nuclear export signals.

摘要: Abstract Nuclear export sequences (NESs) have been identified in many cellular proteins, but it remains unclear how different NESs compare activity. We describe a sensitive new vivo assay which we used to assess the relative activity of types NES. The most common type sequence resembles that first HIV-1 Rev protein and typically comprises core large hydrophobic amino acids specify recognition by CRM1 receptor. compared 10 previously Rev-type our assay, whereas all were functional, activities these signals varied considerably. further 3 from computer database search, each signal was assigned score 1 9 ranked order (e.g., PKI > c-ABL Ran-BP1 FMRP PML IκB-α hdm2). weakest found p53 tumor suppressor p53-regulated proteins p21 hdm2, are normally localized nucleus. All inactivated mutation key residues treatment with CRM1-specific inhibitor, leptomycin B. In contrast, signal, KNS shuttling element derived hnRNP K, exhibited modest insensitive B treatment. thus appears mediate via CRM1-independent pathway. Mutagenesis identified, for time, specific serines acidic necessary its activity, thereby distinguishing other nuclear transport signal. shown can vary profoundly therefore conclude rate largely depends on both strength accessibility