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#muscle cells

6 public questions tagged with this topic.

Cytoskeleton

Which protein is responsible for anchoring actin filaments to the Z-disc in muscle cells?

Organization of sarcomere depends on anchoring thin filaments at Z disc providing mechanical integrity during repetitive contraction. Z disc 100 nanometer thick electron dense structure contains alpha actinin antiparallel dimer crosslinking antiparallel barbed ends from adjacent sarcomeres into orthogonal lattice spaced 20 nanometer, plus titin Z repeats, telethonin, myotilin, FATZ. Nebulin huge filamentous protein 600 to 900 kilodalton with 185 repeats of 35 residue nebulin motif SDXXYK each binding one actin monomer, plus N terminus interacting with tropomodulin capping pointed end and C ter

Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 17: Nebulin Anchoring Actin at Z-Disc.

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Cell Division

Which of the following cells do not divide after differentiation?

Proliferative capacity varies markedly among differentiated tissues, with some lineages retaining ability to re-enter cycle while others become permanently postmitotic. Neurons illustrate irreversible exit: during corticogenesis, progenitor neuroepithelial cells divide, but committed neuroblasts after final mitosis migrate to cortical plate, extend axons and dendrites, and upregulate Cip/Kip inhibitors p27Kip1 and p57Kip2, maintaining retinoblastoma protein in hypophosphorylated state bound to E2F, repressing promoters of cyclins, PCNA, and MCM helicases through transcription factors REST/NRSF

Ref: Becker & Bonni, Progress in Brain Research 2004, Postmitotic Neurons. Alberts 7th ed., Chapter 22.

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Cell Communication and Cell Adhesion

Dystrophin links actin cytoskeleton to

Dystroglycan–ECM complex, is consistent with established principles of cell signaling, receptor pharmacology and cellular regulation. Experimental measurements of binding parameters, genetic loss-of-function studies and pharmacological interventions all converge on the same interpretation. Related options address neighboring concepts but do not satisfy the precise criterion stated in the question.

Ref: NCERT Biology Class 11–12 Alberts et al Molecular Biology of the Cell Lodish et al, Molecular Cell Biology Cooper & Hausman, The Cell Abbas et al., Cellular and Molecular Immunology (for immunology sections)

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