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Joined 2026-09-21 Message
Incoming links: Collagenase
A 1984 primary experiment localized IP3-evoked release using pancreatic acinar cells isolated from rat pancreas with collagenase. A homogenized preparation was separated by differential centrifugation, then by a sucrose step density gradient or precipitation with magnesium chloride. The readout was IP3-induced calcium release per mass of protein across fractions. Release tracked two endoplasmic reticulum markers, RNA content and an enzyme activity, across several separation methods. Marker activities for mitochondria and the cell membrane supplied contrasting comparisons: release correlated negatively with them.[ref]
Effect of inositol-1,4,5-trisphosphate on isolated subcellular fractions of rat pancreas by H. Streb and others. Streb, Bayerdörffer, Haase, Irvine and Schulz, Effect of inositol-1,4,5-trisphosphate on isolated subcellular fractions of rat pancreas (1984), abstract: preparation, separation methods, protein-normalized release and marker correlations
Agreement across distinct fractionations supports an endoplasmic reticulum-associated source in this preparation. “Nonmitochondrial” alone only excludes a candidate; positive compartment markers add localization evidence. Marker comparisons control the localization inference, rather than replacing a no-IP3 release comparison. Fractionation may mix or damage compartments, and correlation does not itself identify the IP3 receptor protein. This calcium release readout also does not directly measure secretion or establish identical responses in every biological cell.