#protein complex

Drosophila -ll

Protein complex restricting dorsal protein:

Dorsal protein activity gradient depends on physical sequestration by Cactus inhibitor forming stable cytoplasmic heterodimer covering Dorsal nuclear localization signal and DNA-binding domain. Complex concentration high dorsally where Cactus unphosphorylated, low ventrally where Toll signaling triggers Pelle kinase phosphorylation and Slimb-mediated degradation. Gurken-Torpedo regulates follicle Pipe transcription upstream, Pipe-Spatzle regulates Toll ligand processing extracellularly, Wingless-Frizzled regulates segment polarity maintenance. Dorsal-Cactus interaction therefore represents fin

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 9: Dorsal-Cactus complex restricting nuclear translocation - ventral degradation.

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Fertilization in mammals-lll

Protein complex essential for morula compaction:

Compaction of eight-cell morula into tightly adherent structure critical for blastocyst formation relies on calcium-dependent adhesion complex E-cadherin, beta-catenin, alpha-catenin and actin. Homophilic E-cadherin bonds stabilize blastomere contacts, intracellularly recruiting beta-catenin which anchors to cytoskeleton enabling polarization, increased compaction and sealing. This complex activates downstream Hippo signaling distinctions between inside and outside cells. Actin-myosin contractility participates downstream, but tubulin-kinesin or dynactin complexes are not primary drivers. Gene

Ref: Stephenson et al., Development 2010: Cadherin-catenin complex essential for morula compaction and cell polarity.

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Cell Cycle Regulation

Which protein complex silences the spindle checkpoint once all chromosomes are attached?

Silencing of spindle assembly checkpoint once all chromosomes achieve correct bi-orientation requires active disassembly of mitotic checkpoint complex and removal of checkpoint proteins from attached kinetochores. Central regulator is p31comet, also called MAD2L1BP, adaptor that binds closed conformation of Mad2 within MCC and recruits ATPase TRIP13 (Pch2 in yeast). TRIP13 uses ATP hydrolysis to convert closed Mad2 back to open inactive form, promoting disassociation of BubR1-Bub3-Cdc20 complex and freeing Cdc20 to activate APC/C. p31comet also competes with Mad1 for Mad2 binding, preventing n

Ref: Mapelli & Musacchio, EMBO J 2007, p31comet and TRIP13; Eytan et al., PNAS 2014, MCC Disassembly.

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Cell Signaling Dev Bio & Other Pathways

γ-secretase complex contains all EXCEPT

ADAM10, 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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