Quantitative comparison of IMAC and TiO2 surfaces used in the study of regulated, dynamic protein phosphorylation.

Protein phosphorylation regulates many aspects of cellular function, including cell proliferation, migration, and signal transduction. An efficient strategy to isolate phosphopeptides from a pool of unphosphorylated peptides is essential to global characterization using mass spectrometry. We describe an approach employing isotope tagging reagents for relative and absolute quantification (iTRAQ) labeling to compare quantitatively commercial and prototypal immobilized metal affinity chelate (IMAC) and metal oxide resins.

The metalloproteinase inhibitor TIMP-2 is down-regulated by androgens in LNCaP prostate carcinoma cells.

Tissue inhibitors of metalloproteinases (TIMPs) have been shown to perform several biological functions in tumor promotion, principally by their action of inhibiting matrix metalloproteinases (MMPs) at different steps of the metastatic process. In particular, TIMP-2 is involved in a functional complex with the membrane-type 1 (MT1) MMP to convert the secreted MMP-2 progelatinase into the fully active proteolytic enzyme. We used the human, androgen-sensitive prostate carcinoma cell line LNCaP in coculture with the human osteosarcoma cell line OHS to experimentally address the possibility of androgen-dependent regulatory effects on the functional MT1-MMP/TIMP-2/MMP-2 complex upon interaction between prostate carcinoma and osteoblastic cells in metastasis of prostate cancer to bone.

Corepressor SMRT functions as a coactivator for thyroid hormone receptor T3Ralpha from a negative hormone response element.

Nuclear receptors are ligand-modulated transcription factors that transduce the presence of lipophilic ligands into changes in gene expression. Nuclear receptor activity is regulated by ligand-induced interactions with coactivator or corepressor molecules. From a positive hormone response element (pHRE) and in the absence of hormone, corepressors SMRT and N-CoR are bound to some nuclear receptors such as the thyroid hormone (T3Rs) and retinoic acid receptors and mediate inhibition of basal levels of transcription.