Statherin Function — MFDS Part 1 MCQ

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HardPhysiologyStatherin FunctionMFDS Part 1

Saliva is normally supersaturated with calcium phosphate yet remains metastable. Loss of statherin would most directly impair which salivary mechanism?

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Correct answer: B — Inhibition of spontaneous calcium phosphate precipitation and seeded hydroxyapatite crystal growth

Explanation lettering: B = shown as A · A = shown as B

A is correct. Statherin is an acidic phosphorylated salivary protein whose adsorption to calcium phosphate and hydroxyapatite inhibits both primary, spontaneous precipitation and secondary, surface-induced crystal growth. This helps saliva remain supersaturated with calcium and phosphate without indiscriminate mineral precipitation, preserving ions relevant to enamel mineral homeostasis. Starch hydrolysis is performed by salivary alpha-amylase (B), whereas cleavage of bacterial peptidoglycan is a function of lysozyme (C). Salivary viscosity and lubrication are principally provided by mucins forming hydrated viscoelastic films (D). Dimeric IgA is transported across salivary gland epithelium by the polymeric immunoglobulin receptor and released as secretory IgA (E). Statherin may influence mineral accretion, but it should not be described simply as preventing calculus formation because calculus development is multifactorial.

Reference: Schwartz SS, Hay DI, Schluckebier SK. Inhibition of calcium phosphate precipitation by human salivary statherin: structure-activity relationships. Calcified Tissue International. 1992;50(6):511–517. https://pubmed.ncbi.nlm.nih.gov/1525706/