The Protein Binding Partners of Copine A in Dictyostelium discoideum
Copyright 2011 by Dr. Cynthia Damer. In accordance with Title 17 of the United States Code, Copyright Law of the United States of America, this material is copyrighted, and any further reproduction or distribution is prohibited without the permission of the copyright owner.
Copine; Actin; Cytoskeleton; Dictyostelium discoideum; Protein binding; Membrane proteins;
Copines make up a multigene family of calcium-dependent, phospholipid-binding proteins. Copine proteins consists of two C2 domains at the N terminus followed by an "A domain" similar to the von Willebrand-Integrin A domain. Mutant studies of copines suggest that copines may be involved in signaling pathways and may play a significant role in cell differentiation, programmed cell death, and cell development. Copines need to be studied further to have a clear understanding of the function they play in organismal life processes. We are studying copine protein function in the model organism protozoan Dictyostelium discoideum. Previous research showed that the copine A (cpnA-) knockout strain of Dictyostelium exhibited normal growth rates, a slight cytokinesis defect, a developmental defect, and a defect in contractile vacuole function. Furthermore, real-time reverse transcription-PCR data suggested that all of the copine genes except cpnF may be important regulators of Dictyostelium development. To fully understand the function of copines in Dictyostelium, it is critical to identify their target proteins. In this study we investigated the proteins that interact with Copine A by using the yeast two-hybrid system. The yeast two-hybrid system is a technique used to identify genes that code for proteins that are associated with a certain protein in vivo. We identified candidate genes DAip1, corA, efaA1, capB, sun1, and rpl3 as coding for binding partners of the Copine A protein. The proteins DAip1, CorA, and EfaAl are associated with actin filament organization in Dictyostelium suggesting that CpnA may have a role in regulating the actin cytoskeleton. The mutant phenotype observed in the cpnA- cells is consistent with a defect in actin filament regulation. McNair Scholar project. Faculty Advisor: Damer, Cynthia Kay, College of Science and Technology.