Importin a is nuclear transport receptor that recognises nuclear localisation sequences (NLS). The protein has two domains: armadillo (ARM) repeats containing NLS-binding sites and the importin beta-binding (IBB) domain. The IBB domain mimics an NLS and can bind to the ARM repeats, preventing NLS binding. This phenomenon, called auto-inhibition, is a key regulatory feature for binding and release of NLS-containing cargo by importin alpha and mutants that lack auto-inhibition show impaired viability in Saccharomyces cerevisiae. The genome of the human malaria parasite, Plasmodium falciparum, contains a single gene for importin alpha and here we show that the native protein expressed by this gene lacks auto-inhibition, suggesting that P. falciparum parasites possess unconventional mechanisms for regulation of cargo binding and release. Mutation of a single SKR motif (conserved in Plasmodium species) to KRR in P. falciparum importin a restores auto-inhibition. This is the first report of alpha single-celled eukaryote that has evolved with a single importin alpha isoform lacking auto-inhibition. (C) 2018 Elsevier Inc. All rights reserved.