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Updated: Dec 23, 2025

Pull-down of Calmodulin-binding Proteins
Published on: January 23, 2012
Ca2+ functions as a molecular switch that controls the mutually exclusive complex formation of pyridoxal phosphatase
Elisabeth Jeanclos1,2,3, Gunnar Knobloch1,2, Axel Hoffmann1,2,4
1Institute of Pharmacology and Toxicology, University of Würzburg, Germany.
Abstract:
Pyridoxal 5'-phosphate (PLP) is an essential cofactor for neurotransmitter metabolism. Pyridoxal phosphatase (PDXP) deficiency in mice increases PLP and γ-aminobutyric acid levels in the brain, yet how PDXP is regulated is unclear. Here, we identify the Ca2+ - and integrin-binding protein 1 (CIB1) as a PDXP interactor by yeast two-hybrid screening and find a calmodulin (CaM)-binding motif that overlaps with the PDXP-CIB1 interaction site. Pulldown and crosslinking assays with purified proteins demonstrate that PDXP directly binds to CIB1 or CaM. CIB1 or CaM does not alter PDXP phosphatase activity. However, elevated Ca2+ concentrations promote CaM binding and, thereby, diminish CIB1 binding to PDXP, as both interactors bind in a mutually exclusive way. Hence, the PDXP-CIB1 complex may functionally differ from the PDXP-Ca2+ -CaM complex.
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