5w4g

Structural highlights

Function

[IMA1_MOUSE] Functions in nuclear protein import as an adapter protein for nuclear receptor KPNB1. Binds specifically and directly to substrates containing either a simple or bipartite NLS motif. Docking of the importin/substrate complex to the nuclear pore complex (NPC) is mediated by KPNB1 through binding to nucleoporin FxFG repeats and the complex is subsequently translocated through the pore by an energy requiring, Ran-dependent mechanism. At the nucleoplasmic side of the NPC, Ran binds to importin-beta and the three components separate and importin-alpha and -beta are re-exported from the nucleus to the cytoplasm where GTP hydrolysis releases Ran from importin. The directionality of nuclear import is thought to be conferred by an asymmetric distribution of the GTP- and GDP-bound forms of Ran between the cytoplasm and nucleus. [DPOLL_HUMAN] Repair polymerase. Involved in base excision repair (BER) responsible for repair of lesions that give rise to abasic (AP) sites in DNA. Has both DNA polymerase and terminal transferase activities. Has a 5'-deoxyribose-5-phosphate lyase (dRP lyase) activity.^{[1] [2]}

References

1. ↑ Garcia-Diaz M, Bebenek K, Kunkel TA, Blanco L. Identification of an intrinsic 5'-deoxyribose-5-phosphate lyase activity in human DNA polymerase lambda: a possible role in base excision repair. J Biol Chem. 2001 Sep 14;276(37):34659-63. Epub 2001 Jul 16. PMID:11457865 doi:10.1074/jbc.M106336200
2. ↑ Maga G, Ramadan K, Locatelli GA, Shevelev I, Spadari S, Hubscher U. DNA elongation by the human DNA polymerase lambda polymerase and terminal transferase activities are differentially coordinated by proliferating cell nuclear antigen and replication protein A. J Biol Chem. 2005 Jan 21;280(3):1971-81. Epub 2004 Nov 10. PMID:15537631 doi:10.1074/jbc.M411650200