Belinda J. Westman

Learn More
Cells typically respond quickly to stress, altering their metabolism to compensate. In mammalian cells, stress signaling usually leads to either cell-cycle arrest or apoptosis, depending on the severity of the insult and the ability of the cell to recover. Stress also often leads to reorganization of nuclear architecture, reflecting the simultaneous(More)
MicroRNAs (miRNAs) repress translation of target mRNAs by interaction with partially mismatched sequences in their 3' UTR. The mechanism by which they act on translation has remained largely obscure. We examined the translation of mRNAs containing four partially mismatched miRNA-binding sites in the 3' UTR in HeLa cells cotransfected with a cognate miRNA.(More)
Protein modification by conjugation of small ubiquitin-related modifier (SUMO) is involved in diverse biological functions, such as transcription regulation, subcellular partitioning, stress response, DNA damage repair, and chromatin remodeling. Here, we show that the serine/arginine-rich protein SF2/ASF, a factor involved in splicing regulation and other(More)
Posttranslational SUMO modification is an important mechanism of regulating protein function, especially in the cell nucleus. The nucleolus is the subnuclear organelle responsible for rRNA synthesis, processing, and assembly of the large and small ribosome subunits. Here, we have used SILAC-based quantitative proteomics to identify nucleolar SUMOylated(More)
The 22 kDa haem-binding protein, p22HBP, is highly expressed in erythropoietic tissues and binds to a range of metallo- and non-metalloporphyrin molecules with similar affinities, suggesting a role in haem regulation or synthesis. We have determined the three-dimensional solution structure of p22HBP and mapped the porphyrin-binding site, which comprises a(More)
MicroRNAs (miRs) are an important class of gene regulators that affect a wide range of biological processes. Despite the early recognition of miRs as translational regulators and intense interest in studying this phenomenon, it has so far not been possible to derive a consensus model for the underlying molecular mechanism(s). The potential of miRs to act in(More)
The oligomerization domain that is present at the C terminus of Ikaros-family proteins and the protein Trps-1 is important for the proper regulation of developmental processes such as hematopoiesis. Remarkably, this domain is predicted to contain two classical zinc fingers (ZnFs), domains normally associated with the recognition of nucleic acids. The(More)
A role for SUMOylation in the biogenesis and/or function of Box C/D snoRNPs has been reported, mediated via SUMO2 conjugation to the core snoRNP protein, Nop58. A quantitative proteomics screen, based on SILAC (stable-isotope labeling by amino acids in cell culture) and mass spectrometry using extracts prepared from cultured mammalian cells expressing(More)
In vitro, assembly of box C/D small nucleolar ribonucleoproteins (snoRNPs) involves the sequential recruitment of core proteins to snoRNAs. In vivo, however, assembly factors are required (NUFIP, BCD1, and the HSP90-R2TP complex), and it is unknown whether a similar sequential scheme applies. In this paper, we describe systematic quantitative stable isotope(More)