biostudies-literatureMomand JNational Key Basic Research ProgramNSF-Center for Research Excellence in Science and Technology ProgramNational Institute of General Medical SciencesNIGMS NIH HHS1328-1337https://www.ebi.ac.uk/biostudies/studies/S-EPMC5586343biostudies-literatureUnknown7(9)t-Darpp (truncated isoform of dopamine- and cAMP-regulated phosphoprotein) is a protein encoded by the <i>PPP1R1B</i> gene and is expressed in breast, colon, esophageal, gastric, and prostate cancers, as well as in normal adult brain striatal cells. Overexpression of t-Darpp in cultured cells leads to increased protein kinase A activity and increased phosphorylation of AKT (protein kinase B). In HER2+ breast cancer cells, t-Darpp confers resistance to the chemotherapeutic agent trastuzumab. To shed light on t-Darpp function, we studied its secondary structure, oligomerization status, metal-binding properties, and phosphorylation by cyclin-dependent kinases 1 and 5. t-Darpp exhibits 12% alpha helix, 29% beta strand, 24% beta turn, and 35% random coil structures. It binds calcium, but not other metals commonly found in biological systems. The T39 site, critical for t-Darpp activation of the AKT signaling pathway, is a substrate for phosphorylation by cyclin-dependent kinase 1 and cyclin-dependent kinase 5. Gel filtration chromatography, sedimentation equilibrium analysis, blue native gel electrophoresis, and glutaraldehyde-mediated cross-linking experiments demonstrate that the majority of t-Darpp exists as a monomer, but forms low levels (< 3%) of hetero-oligomers with its longer isoform Darpp-32. t-Darpp has a large Stokes radius of 4.4 nm relative to its mass of 19 kDa, indicating that it has an elongated structure.FEBS open biot-Darpp is an elongated monomer that binds calcium and is phosphorylated by cyclin-dependent kinases 1 and 5.PMC55863432014CB744502NSF HRD 1547723R01 GM1058981RO1GM105898Kane SEMonterroso EMagdziarz PFeng YJiang DCelis AWang XZhou FMomand JDenny EParga EPhillips MLfalset-Darpp is an elongated monomer that binds calcium and is phosphorylated by cyclin-dependent kinases 1 and 5.t-Darpp (truncated isoform of dopamine- and cAMP-regulated phosphoprotein) is a protein encoded by the <i>PPP1R1B</i> gene and is expressed in breast, colon, esophageal, gastric, and prostate cancers, as well as in normal adult brain striatal cells. Overexpression of t-Darpp in cultured cells leads to increased protein kinase A activity and increased phosphorylation of AKT (protein kinase B). In HER2+ breast cancer cells, t-Darpp confers resistance to the chemotherapeutic agent trastuzumab. To shed light on t-Darpp function, we studied its secondary structure, oligomerization status, metal-binding properties, and phosphorylation by cyclin-dependent kinases 1 and 5. t-Darpp exhibits 12% alpha helix, 29% beta strand, 24% beta turn, and 35% random coil structures. It binds calcium, but not other metals commonly found in biological systems. The T39 site, critical for t-Darpp activation of the AKT signaling pathway, is a substrate for phosphorylation by cyclin-dependent kinase 1 and cyclin-dependent kinase 5. Gel filtration chromatography, sedimentation equilibrium analysis, blue native gel electrophoresis, and glutaraldehyde-mediated cross-linking experiments demonstrate that the majority of t-Darpp exists as a monomer, but forms low levels (< 3%) of hetero-oligomers with its longer isoform Darpp-32. t-Darpp has a large Stokes radius of 4.4 nm relative to its mass of 19 kDa, indicating that it has an elongated structure.2017-01-01T00:00:00Z2017 Sep2024-10-17T15:11:55.924Z2019-03-27T02:55:35ZS-EPMC55863432890486210.1002/2211-5463.12269