De novo sequencing and construction of a unique antibody for the recognition of alternative conformations of cytochrome in cells.

Cytochrome (cyt ) can undergo reversible conformational changes under biologically relevant conditions. Revealing these alternative cyt conformers at the cell and tissue level is challenging. A monoclonal antibody (mAb) identifying a key conformational change in cyt was previously reported, but the hybridoma was rendered nonviable.

Paradoxical Roles of Leucine-Rich α-Glycoprotein-1 in Cell Death and Survival Modulated by Transforming Growth Factor-Beta 1 and Cytochrome .

Leucine-rich α-glycoprotein-1 (LRG1) has been shown to impact both apoptosis and cell survival, pleiotropic effects similar to one of its known ligands, transforming growth factor-beta 1 (TGF-β1). Recent studies have given insight into the TGF-β1 signaling pathways involved in LRG1-mediated death versus survival signaling, i.e.

Intracellular leucine-rich alpha-2-glycoprotein-1 competes with Apaf-1 for binding cytochrome c in protecting MCF-7 breast cancer cells from apoptosis.

Leucine-rich alpha-2-glycoprotein-1 (LRG1) has been shown to compete with apoptosis activating factor-1 (Apaf-1) for binding cytochrome c (Cyt c) and could play a role in inhibition of apoptosis. Employing MCF-7 breast cancer cells, we report that intracellular LRG1 does protect against apoptosis. Thus, cells transfected with the lrg1 gene and expressing higher levels of LRG1 were more resistant to hydrogen peroxide-induced apoptosis than parental cells, while cells in which LRG mRNA was knocked down by short hairpin (sh) RNA-induced degradation were more sensitive.

Alternative Conformations of Cytochrome c: Structure, Function, and Detection.

Cytochrome c (cyt c) is a cationic hemoprotein of ∼100 amino acid residues that exhibits exceptional functional versatility. While its primary function is electron transfer in the respiratory chain, cyt c is also recognized as a key component of the intrinsic apoptotic pathway, the mitochondrial oxidative protein folding machinery, and presumably as a redox sensor in the cytosol, along with other reported functions. Transition to alternative conformations and gain-of-peroxidase activity are thought to further enable the multiple functions of cyt c and its translocation across cellular compartments.