Cofilin recruits F-actin to SPCA1 and promotes Ca2+-mediated secretory cargo sorting.
Bottom Line: How these proteins interact and activate the pump to facilitate cargo sorting, however, is not known.A 132-amino acid portion of the SPCA1 phosphorylation domain (P-domain) interacted with actin in a CFL-1-dependent manner.Altogether, our findings reveal the mechanism of CFL-1-dependent recruitment of actin to SPCA1 and the significance of this interaction for Ca(2+) influx and secretory cargo sorting.
Affiliation: Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.Show MeSH
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Mentions: To test the actin recruitment to the SPCA1 domains in the presence or absence of CFL-1 as well as CFL-1-S3E, the proteins were attached to the beads and incubated with fluorescently labeled actin as described in the Materials and methods. Actin did not associate to His-Sumo, or to His Sumo-SPCA1-L1 in either the absence or the presence of CFL-1 or CFL-1-S3E (Fig. 3 A). In contrast, although His-Sumo-SPCA1-L2-C1 did not interact with actin in the absence of CFL-1 or in the presence of CFL-1-S3E, the actin filaments were strongly recruited after recombinant CFL-1 was added (Fig. 3 A). To quantify our results, we examined 10 beads in three independent experiments and quantified the amount of labeled actin recruited to the beads by calculating the fluorescence ratio of the area close to the bead surface to the intensity of the background (Fig. 3 B).
Affiliation: Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.