Publications by authors named "John C Gaipa"

2 Publications

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Structure of the polycomb group protein PCGF1 in complex with BCOR reveals basis for binding selectivity of PCGF homologs.

Structure 2013 Apr 21;21(4):665-71. Epub 2013 Mar 21.

Department of Biochemistry and CTRC, University of Texas Health Science Center at San Antonio, MSC 7760, 7703 Floyd Curl Drive, San Antonio, TX 78229-3990, USA.

Polycomb-group RING finger homologs (PCGF1, PCGF2, PCGF3, PCGF4, PCGF5, and PCGF6) are critical components in the assembly of distinct Polycomb repression complex 1 (PRC1)-related complexes. Here, we identify a protein interaction domain in BCL6 corepressor, BCOR, which binds the RING finger- and WD40-associated ubiquitin-like (RAWUL) domain of PCGF1 (NSPC1) and PCGF3 but not of PCGF2 (MEL18) or PCGF4 (BMI1). Because of the selective binding, we have named this domain PCGF Ub-like fold discriminator (PUFD). The structure of BCOR PUFD bound to PCGF1 reveals that (1) PUFD binds to the same surfaces as observed for a different Polycomb group RAWUL domain and (2) the ability of PUFD to discriminate among RAWULs stems from the identity of specific residues within these interaction surfaces. These data show the molecular basis for determining the binding preference for a PCGF homolog, which ultimately helps determine the identity of the larger PRC1-like assembly.
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http://dx.doi.org/10.1016/j.str.2013.02.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4003909PMC
April 2013

Enhanced Two-Stage Reactive Polymer Network Forming Systems.

Polymer (Guildf) 2012 May 14;53(12):2429-2434. Epub 2012 Apr 14.

Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO, USA.

In this study, we develop thiol/acrylate two-stage reactive network forming polymer systems that exhibit two distinct and orthogonal stages of curing. Using a thiol-acrylate system with excess acrylate functional groups, a first stage polymer network is formed via a 1 to 1 stoichiometric thiol-acrylate Michael addition reaction (stage 1). At a later point in time, the excess acrylate functional groups are homopolymerized via a photoinitiated free radical polymerization to form a second stage polymer network (stage 2). By varying the monomers within the system as well as the stoichiometery of the thiol to acrylate functional groups, we demonstrate the ability of the two-stage polymer network forming systems to encompass a wide range of properties at the end of both the stage 1 and stage 2 polymerizations. Using urethane di- and hexa-acrylates within the formulations led to two-stage reactive polymeric systems with stage 1 T(g)s that ranged from -12 to 30 °C. The systems were then photocured, upon which the T(g) of the systems increases by up to 90 °C while also achieving a nearly 20 fold modulus increase.
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http://dx.doi.org/10.1016/j.polymer.2012.04.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3392718PMC
May 2012