Identification of a high-affinity Ca sup 2+ pump associated with endocytotic vesicles in Dictyostelium discoideum

Journal Article · Wed Nov 01 00:00:00 EST 1989 · Experimental Cell Research; (United States)

DOI:https://doi.org/10.1016/0014-4827(89)90033-5· OSTI ID:5622952

Milne, J L; Coukell, M B ^[1]

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1. York Univ., North York, Ontario (Canada)

In the cellular slime mold Dictyostelium discoideum, changes in free cytosolic Ca{sup 2+} are thought to regulate certain processes during cell aggregation and differentiation. To understand the mechanisms controlling free Ca{sup 2+} levels in this organism, the authors previously isolated and characterized an ATP/Mg{sup 2+}-dependent, high-affinity Ca{sup 2+} pump which appeared to be a component of inside-out plasma membrane vesicles. In this report, they demonstrate that a high-affinity Ca{sup 2+} pump, with properties virtually identical to the isolated pump, can be detected in filipin- or digitonin-permeabilized cells of Dictyostelium. Moreover, Ca{sup 2+}-pumping vesicles, which migrate on Percoll/KCl gradients like the vesicles identified earlier, can be isolated from the permeabilized cells. Results of additional experiments suggest that this intracellular Ca{sup 2+} transporter is associated with a high-capacity non-IP{sub 3}-releasable Ca{sup 2+} store which is generated by endocytosis. A possible role for this store in maintaining Ca{sup 2+} homeostasis in Dictyostelium is discussed.

• OSTI ID: 5622952
• Journal Information: Experimental Cell Research; (United States), Vol. 185:1; ISSN 0014-4827
• Country of Publication: United States
• Language: English

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