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tRNA (Ser)Sec coexpression affects SECp43 levels in HEK 293 cells
Author(s) -
Gilman Christy Leinaala,
Seale Lucia A,
Seyedali Ali,
Berry Marla J
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.916.13
Subject(s) - selenocysteine , transfer rna , cytosol , biology , amino acid , chemistry , hek 293 cells , biochemistry , microbiology and biotechnology , rna , gene , enzyme , cysteine
Selenium is present in the active site(s) of selenoproteins in the form of selenocysteine (sec), the 21st amino acid. Sec is incorporated cotranslationally into proteins through recoding of the UGA codon. Key factors in this process include a unique tRNA for Sec (Sec‐tRNA), SECIS elements, SBP2 and EFsec. Additional factors include SLA/LP, SPS1 and SECp43. Previous studies in our laboratory have found that cotransfection of these three factors resulted in coprecipitation in nuclear and cytosolic fractions, indicating the formation of complexes. In GST pull downs, SECp43 and SPS1 coimmunoprecipitate in the cytosol in the absence but not in the presence of Sec‐tRNA. SECp43 is present in the nuclear fraction in the absence of other factors, in either the absence or presence of Sec‐tRNA. SECp43 pull‐down of SPS1 or vice versa is not seen when SLA/LP is added, suggesting mutually exclusive interactions. SECp43 in the presence of SLA/LP pellets with V5 beads independent of V5 tagged protein, suggesting it may be part of a large complex. This is not seen when SPS1 is also present, further supporting mutually exclusive interactions. We are currently following up on these findings to elucidate the mechanism by which Sec‐tRNA affects SECp43 levels and to understand the interactions of these factors. Supported by NIH grant DK‐47320 to MJB.