Transportin 1 is a major nuclear import receptor of the nitric oxide synthase interacting protein

ABSTRACT: The nitric oxide synthase interacting protein (NOSIP), an E3-ubiquitin ligase, is involved in various processes like neuronal development, craniofacial development, granulopoiesis, mitogenic signaling, apoptosis and cell proliferation. The best characterized function of NOSIP is the regulation of eNOS (endothelial nitric oxide synthase) activity by translocating the membrane bound enzyme to the actin-skeleton, specifically in the G2 phase of the cell cycle. For this, NOSIP itself has to be translocated from its prominent localization, the nucleus, to the cytoplasm. Nuclear import of NOSIP was suggested to be mediated by the canonical transport receptors importin /. Recently, we found NOSIP in a proteomic screen as a potential importin 13 cargo. Here, we describe the nuclear shuttling characteristics of NOSIP in vivo and in vitro and show that it does not interact directly with importin . Instead, it formed stable complexes with several importins (-, -7, -/7, -5, -13 and transportin 1) and was imported into the nucleus in digitonin-permeabilized cells. In vivo, transportin 1 seems to be the major nuclear transport receptor. A detailed analysis of the NOSIP-transportin 1 interaction revealed an unusual binding mode, involving the N-terminal half of transportin 1. In contrast to nuclear import, nuclear export of NOSIP seems to occur mostly by passive diffusion.

INSTRUMENT(S): Orbitrap Exploris 480, Q Exactive HF

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Henning Urlaub  

LAB HEAD: Prof. Henning Urlaub

PROVIDER: PXD033966 | Pride | 2023-03-10

REPOSITORIES: Pride