Recognition motifs for importin 4 [(L)PPRS(G/P)P] and importin 5 [KP(K/Y)LV] binding, identified by bio-informatic simulation and experimental in vitro validation

Athanasios A Panagiotopoulos; Konstantina Kalyvianaki; Paraskevi K Tsodoulou; Maria N Darivianaki; Dimitris Dellis; George Notas; Vangelis Daskalakis; Panayiotis A Theodoropoulos; Christos Α Panagiotidis; Elias Castanas; Marilena Kampa

doi:10.1016/j.csbj.2022.10.015

Recognition motifs for importin 4 [(L)PPRS(G/P)P] and importin 5 [KP(K/Y)LV] binding, identified by bio-informatic simulation and experimental in vitro validation

Comput Struct Biotechnol J. 2022 Oct 26:20:5952-5961. doi: 10.1016/j.csbj.2022.10.015. eCollection 2022.

Affiliations

¹ Laboratory of Experimental Endocrinology, School of Medicine, University of Crete, 71013, Greece.
² Laboratory of Pharmacology, School of Pharmacy, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece.
³ National Infrastructures for Research and Technology, Athens 11523, Greece.
⁴ Department of Chemical Engineering, Cyprus University of Technology, Limassol, Cyprus.
⁵ Laboratory of Biochemistry, School of Medicine, University of Crete, 71013, Greece.

Abstract

Nuclear translocation of large proteins is mediated through karyopherins, carrier proteins recognizing specific motifs of cargo proteins, known as nuclear localization signals (NLS). However, only few NLS signals have been reported until now. In the present work, NLS signals for Importins 4 and 5 were identified through an unsupervised in silico approach, followed by experimental in vitro validation. The sequences LPPRS(G/P)P and KP(K/Y)LV were identified and are proposed as recognition motifs for Importins 4 and 5 binding, respectively. They are involved in the trafficking of important proteins into the nucleus. These sequences were validated in the breast cancer cell line T47D, which expresses both Importins 4 and 5. Elucidating the complex relationships of the nuclear transporters and their cargo proteins is very important in better understanding the mechanism of nuclear transport of proteins and laying the foundation for the development of novel therapeutics, targeting specific importins.

Keywords: IPO4, Importin 4; IPO5, Importin 5; IPO7, Importin 7; IPOα, Importin α; IPOβ, Importin β; Importin 4; Importin 5; Karyopherins; Nuclear localization signal (NLS).