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Co‐activation of RanGTPase and inhibition of GTP dissociation by Ran‐GTP binding protein RanBP1.
Author(s) -
Bischoff F.R.,
Krebber H.,
Smirnova E.,
Dong W.,
Ponstingl H.
Publication year - 1995
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1995.tb07049.x
Subject(s) - mitosis , biology , german , cell division , genetics , philosophy , linguistics , cell
RCC1 (the regulator of chromosome condensation) stimulates guanine nucleotide dissociation on the Ras‐related nuclear protein Ran. Both polypeptides are components of a regulatory pathway that has been implicated in regulating DNA replication, onset of and exit from mitosis, mRNA processing and transport, and import of proteins into the nucleus. In a search for further members of the RCC1‐Ran signal pathway, we have identified proteins of 23, 45 and 300 kDa which tightly bind to Ran‐GTP but not Ran‐GDP. The purified soluble 23 kDa Ran binding protein RanBP1 does not activate RanGTPase, but increases GTP hydrolysis induced by the RanGTPase‐activating protein RanGAP1 by an order of magnitude. In the absence of RanGAP, it strongly inhibits RCC1‐induced exchange of Ran‐bound GTP. In addition, it forms a stable complex with nucleotide‐free RCC1‐Ran. With these properties, it differs markedly from guanine diphosphate dissociation inhibitors which preferentially prevent the exchange of protein‐bound GDP and in some cases were shown to inhibit GAP‐induced GTP hydrolysis. RanBP1 is the first member of a new class of proteins regulating the binding and hydrolysis of GTP by Ras‐related proteins.