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Internal initiation drives the synthesis of Ure2 protein lacking the prion domain and affects [ URE3 ] propagation in yeast cells
Author(s) -
Komar Anton A.,
Lesnik Thierry,
Cullin Christophe,
Merrick William C.,
Trachsel Hans,
Altmann Michael
Publication year - 2003
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 - 10.1093/emboj/cdg103
Subject(s) - biology , saccharomyces cerevisiae , fungal prion , yeast , translation (biology) , phenotype , catabolism , microbiology and biotechnology , regulator , biochemistry , genetics , gene , messenger rna , metabolism
The [ URE3 ] phenotype in Saccharomyces cerevisiae is caused by the inactive, altered (prion) form of the Ure2 protein (Ure2p), a regulator of nitrogen catabolism. Ure2p has two functional domains: an N‐terminal domain necessary and sufficient for prion propagation and a C‐terminal domain responsible for nitrogen regulation. We show here that the mRNA encoding Ure2p possesses an IRES (internal ribosome entry site). Internal initiation leads to the synthesis of an N‐terminally truncated active form of the protein (amino acids 94–354) lacking the prion‐forming domain. Expression of the truncated Ure2p form (94–354) mediated by the IRES element cures yeast cells of the [ URE3 ] phenotype. We assume that the balance between the full‐length and truncated (94–354) Ure2p forms plays an important role in yeast cell physiology and differentiation.