Cellular Requirements for CRM 1 Import and Export

Abstract

We studied the cellular requirements for the translocation of CRM 1 (exportin 1) between the nucleus and the cytoplasm. CRM 1 import requires neither ATP, Ran, Ran-dependent GTP hydrolysis, nor a particular temperature. CRM 1 and importin β compete with each other during their import. Thus, CRM 1 is able to enter the nucleus in a manner similar to importinβ. In contrast, the in vivo export of CRM 1 involves ATP-consuming step (s).