#protein activation

Paracrine Factor

Which protein is critical for the activation of Gli transcription factors in the Hedgehog pathway?

Hedgehog-dependent activation of Gli transcription factors requires regulated processing and ciliary trafficking mechanisms. In absence of Hedgehog, Gli2 and Gli3 phosphorylated by PKA, GSK3, CK1 create phosphodegron recognized by beta-TrCP SCF E3 ligase and Sufu sequestration, cleaved to repressor forms Gli3R blocking targets like Patched1, Hhip1. Hedgehog binding to Patched derepresses Smoothened, which accumulates in primary cilium, binds EVC2, inhibits Suppressor of Fused, stabilizing full-length Gli as activator GliA. This Smoothened-dependent conversion in cilium tip, requiring kinesin K

Ref: Huangfu & Anderson, Development 2006: Smoothened ciliary localization required for Gli activator formation in Hedgehog pathway.

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A Cell Signaling

ERK5 full activation requires

MEKK2 and MEK5, 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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Cell Signaling ELR Pathways - I

Ras/MAPK pathway involves

sequential kinase activation, 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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Cell Signaling GPCR Pathways - I

Ca2+/calmodulin complex commonly activates

CaM-dependent kinases, 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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