Signal recognition particle 14 binds to importin α in Plasmodium falciparum

The eukaryotic signal recognition particle (SRP) consists of six proteins and one SRP RNA. This ribonucleoprotein complex assembles inside the nucleus. Nucleocytoplasmic transport is an essential process for the biogenesis of signal recognition particles (SRPs) as well as for the survival of a cell. There are studies on cells that indicate the import receptor is responsible for import of SRP proteins into nucleus, but there is a lack of evidence that SRP proteins directly bind with import receptors.

Coding sequences of SRP 14 and importin α were amplified from synthesized cDNA and genomic DNA, respectively, of Plasmodium falciparum cultivated in vitro culture. The amplified products were cloned and expressed in E. coli, followed by purification. A binding study was conducted on glutathione-agarose as well as in a 96-well plate format at different concentrations of SRP 14 with immobilized importin α.

This is the first report of direct binding between importin α and a eukaryotic signal recognition particle 14 (SRP 14). A cost-effective 96-well plate-based assay has also been developed to study the binding of cargoes of importin α.