Biophysical characterization of a binding site for TLQP-21, a naturally occurring peptide which induces resistance to obesity |
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Authors: | V. Cassina A. Torsello A. Tempestini D. Salerno D. Brogioli L. Tamiazzo E. Bresciani J. Martinez J.A. Fehrentz P. Verdié R.J. Omeljaniuk R. Possenti L. Rizzi V. Locatelli F. Mantegazza |
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Affiliation: | 1. Department of Experimental Medicine, University of Milano-Bicocca, Via Cadore 48, 20900, Monza (MB) Italy;2. Institut de Biomolécules Max Mousseron, UMR 5247, CNRS, Universités Montpellier 1, Montpellier 2, 34093, Montpellier, France;3. Department of Biology, Lakehead University, 955 Oliver Road, Thunder Bay, ON, Canada P7B 5E1;4. Dept Medicine of Systems, University of Rome Tor Vergata, Viale Montpellier 1, and CNR-IFT, 00133, Rome, Italy |
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Abstract: | Recently, we demonstrated that TLQP-21 triggers lipolysis and induces resistance to obesity by reducing fat accumulation [1]. TLQP-21 is a 21 amino acid peptide cleavage product of the neuroprotein VGF and was first identified in rat brain. Although TLQP-21 biological activity and its molecular signaling is under active investigation, a receptor for TLQP-21 has not yet been characterized. We now demonstrate that TLQP-21 stimulates intracellular calcium mobilization in CHO cells. Furthermore, using Atomic Force Microscopy (AFM), we also provide evidence of TLQP-21 binding-site characteristics in CHO cells. AFM was used in force mapping mode equipped with a cantilever suitably functionalized with TLQP-21. Attraction of this functionalized probe to the cell surface was specific and consistent with the biological activity of TLQP-21; by contrast, there was no attraction of a probe functionalized with biologically inactive analogues. We detected interaction of the peptide with the binding-site by scanning the cell surface with the cantilever tip. The attractive force between TLQP-21 and its binding site was measured, statistically analyzed and quantified at approximately 40 pN on average, indicating a single class of binding sites. Furthermore we observed that the distribution of these binding sites on the surface was relatively uniform. |
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