AHNAK: the giant jack of all trades

The nucleoprotein AHNAK is an unusual and somewhat mysterious scaffolding protein characterised by its large size of approximately 700 kDa. Several aspects of this protein remain uncertain, including its exact molecular function and regulation on both the gene and protein levels. Various studies have attempted to annotate AHNAK and, notably, protein interaction and expression analyses have contributed greatly to our current understanding of the protein. The implicated biological processes are, however, very diverse, ranging from a role in the formation of the blood-brain barrier, cell architecture and migration, to the regulation of cardiac calcium channels and muscle membrane repair. In addition, recent evidence suggests that AHNAK might be yet another accomplice in the development of tumour metastasis. This review will discuss the different functional roles of AHNAK, highlighting recent advancements that have added foundation to the proposed roles while identifying ties between them. Implications for related fields of research are noted and suggestions for future research that will assist in unravelling the function of AHNAK are offered.