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#protein processing

4 public questions tagged with this topic.

Paracrine Factor

What role does cholesterol play in Hedgehog protein processing?

Hedgehog proteins undergo unique autoprocessing requiring intein-like activity and lipid modifications for gradient formation. C-terminal domain cleaves N-terminal signaling peptide, covalently attaches cholesterol to C-terminus, and palmitate attaches to N-terminal cysteine via Skinny hedgehog HHAT acyltransferase in endoplasmic reticulum. Cholesterol moiety anchors Hedgehog to membranes of producing cells, restricts diffusion, enables multimeric sterol-rich puncta for long-range gradient and facilitates secretion via Dispatched transporter RND protein requiring sterol sensing domain. Without cholesterol, Hedgehog diffuses uncontrolled but fails to signal at distance, loses apical sorting. Thus lipid modifications crucial for morphogen gradient shaping.

Ref: Porter et al., Science 1996: Cholesterol modification of Hedgehog required for secretion, multimerization and gradient.

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Cell Signaling Dev Bio & Other Pathways

In absence of Hedgehog, Ci is processed into

Repressor, 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 Dev Bio & Other Pathways

Pathogenic APP cleavage generates which peptide?

Aβ42, 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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