Sociology 2152A/B Quiz: QUIZ 2.docx
19 Apr 2013
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Cellular stress responses help ensure the cell"s survival or for elimination of damaged/unwanted cells. Whether the stress is environmental, physiological or pathological, the evolutionarily conserved response is to induce heat shock proteins (hsps). Heat shock proteins act as molecular chaperones to help proteins fold properly, they protect cells from extreme, stressful conditions. Hsps can also inhibit apoptotic pathways by interacting with cytoskeleton to maintain cell integrity. Hsp10, 20-30, and 100 interacts with actin microfilaments of cytoskeleton. Hsp90 constitutively expressed, intracellular, prevents premature folding of nascent polypeptides, and interacts with microtubules of cytoskeleton. Hsp27/70 normal low basal levels, increases in response to environmental & physiological stress, transcription is activated by heat shock factors (hsf). Hsp70 can interact with microtubules, microfilaments and intermediate filaments of the cytoskeleton. Hsf1 master regulator in vertebrates, constitutively expressed, monomeric form interacts with hsp90 in the cytoplasm to stay inactive. With stress, amount of unfolded protein increases and competes with.
