Functional analysis of calcium-binding EF-hand motifs of visinin-like protein-1 |
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Authors: | Lin Lin Braunewell Karl-Heinz Gundelfinger Eckart D Anand Rene |
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Institution: | Neuroscience Center of Excellence, 2020 Gravier Street, Suite D, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA. |
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Abstract: | Visinin-like protein-1 (VILIP-1), a myristoylated calcium sensor protein with three EF-hand motifs, modulates adenylyl cyclase activity. It translocates to membranes when a postulated "calcium-myristoyl switch" is triggered by calcium-binding to expose its sequestered myristoyl moiety. We investigated the contributions of the EF-hand motifs to the translocation of VILIP-1 to membranes and to the modulation of adenylyl cyclase activity. Mutation of residues crucial for binding calcium within each one of the EF-hand motifs indicated that they all contributed to binding calcium. Simultaneous mutations of all of the three EF-hand motifs completely abolished VILIP-1's ability to bind calcium, attenuated but did not eliminate its modulation of adenylyl cyclase activity, and abolished its calcium-dependence for association with cellular membranes. These results show that the calcium-binding EF-hand motifs of VILIP-1 do not have an essential role in modulating adenylyl cyclase activity but instead have a structural role in activating the "calcium-myristoyl switch" of VILIP-1. |
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Keywords: | Visinin-like protein-1 EF-hand Calcium Cyclic AMP Adenylyl cyclase Myristoylation |
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