|
||
J. Cell Biol.,
Volume 143, Number 7, December 28, 1998 1813-1830
Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
We have identified a specific karyopherin
docking complex within the yeast nuclear pore complex
(NPC) that contains two novel, structurally related nucleoporins, Nup53p and Nup59p, and the NPC core
protein Nup170p. This complex was affinity purified
from cells expressing a functional Nup53p-protein A
chimera. The localization of Nup53p, Nup59p, and
Nup170p within the NPC by immunoelectron microscopy suggests that the Nup53p-containing complex is
positioned on both the cytoplasmic and nucleoplasmic
faces of the NPC core. In association with the isolated
complex, we have also identified the nuclear transport
factor Kap121p (Pse1p). Using in vitro binding assays,
we showed that each of the nucleoporins interacts with one another. However, the association of Kap121p with
the complex is mediated by its interaction with Nup53p.
Moreover, Kap121p is the only
-type karyopherin that
binds Nup53p suggesting that Nup53p acts as a specific
Kap121p docking site. Kap121p can be released from
Nup53p by the GTP bound form of the small GTPase Ran. The physiological relevance of the interaction between Nup53p and Kap121p was further underscored
by the observation that NUP53 mutations alter the subcellular distribution of Kap121p and the Kap121p-
mediated import of a ribosomal L25 reporter protein. Interestingly, Nup53p is specifically phosphorylated
during mitosis. This phenomenon is correlated with a
transient decrease in perinuclear-associated Kap121p.
This article has been cited by other articles:
|
|