Feng Guo Department of Biological Chemistry, David Geffen School of Medicine, UCLA, USA
1 protocol

Ian Barr
  • Department of Biological Chemistry, David Geffen School of Medicine, UCLA, USA
Research focus
  • Biochemistry
  • 1 Author merit


Ph.D. in Biological Chemistry, University of California, Los Angeles, 2012

Current position

Postdoctoral Researcher, University of California, Berkeley (2013-present)


  1. Rui, Z., Li, X., Zhu, X., Liu, J., Domigan, B., Barr, I., Cate, J. H. and Zhang, W. (2014). Microbial biosynthesis of medium-chain 1-alkenes by a nonheme iron oxidase. Proceedings of the National Academy of Sciences 111(51): 18237-18242.
  2. Latham, J. A., Iavarone, A. T., Barr, I., Juthani, P. V. and Klinman, J. P. (2015). PqqD is a novel peptide chaperone that forms a ternary complex with the radical S-adenosylmethionine protein PqqE in the pyrroloquinoline quinone biosynthetic pathway. J Biol Chem 290(20): 12908-12918.
  3. Barr, I., Weitz, S. H., Atkin, T., Hsu, P., Karayiorgou, M., Gogos, J. A., Weiss, S. and Guo, F. (2015). Cobalt(III) Protoporphyrin Activates the DGCR8 Protein and Can Compensate microRNA Processing Deficiency. Chem Biol 22(6): 793-802.
  4. Barr, I. and Guo, F. (2014). Primary microRNA processing assay reconstituted using recombinant Drosha and DGCR8. Methods Mol Biol 1095: 73-86.
  5. Weitz, S. H., Gong, M., Barr, I., Weiss, S. and Guo, F. (2014). Processing of microRNA primary transcripts requires heme in mammalian cells. Proc Natl Acad Sci U S A 111(5): 1861-1866.
  6. Senturia, R., Laganowsky, A., Barr, I., Scheidemantle, B. D. and Guo, F. (2012). Dimerization and heme binding are conserved in amphibian and starfish homologues of the microRNA processing protein DGCR8. PLoS One 7(7): e39688.
  7. Meer, E. J., Wang, D. O., Kim, S., Barr, I., Guo, F. and Martin, K. C. (2012). Identification of a cis-acting element that localizes mRNA to synapses. Proc Natl Acad Sci U S A 109(12): 4639-4644.
  8. Barr, I., Smith, A. T., Chen, Y., Senturia, R., Burstyn, J. N. and Guo, F. (2012). Ferric, not ferrous, heme activates RNA-binding protein DGCR8 for primary microRNA processing. Proc Natl Acad Sci U S A 109(6): 1919-1924.
  9. Barr, I., Smith, A. T., Senturia, R., Chen, Y., Scheidemantle, B. D., Burstyn, J. N. and Guo, F. (2011). DiGeorge critical region 8 (DGCR8) is a double-cysteine-ligated heme protein. J Biol Chem 286(19): 16716-16725.
  10. Wang, Q., Barr, I., Guo, F. and Lee, C. (2008). Evidence of a novel RNA secondary structure in the coding region of HIV-1 pol gene. RNA 14(12): 2478-2488.
1 Protocol published
Pyridine Hemochromagen Assay for Determining the Concentration of Heme in Purified Protein Solutions
Authors:  Ian Barr and Feng Guo, date: 09/20/2015, view: 28144, Q&A: 2
Heme is a common cofactor in proteins, found in hemoglobin, myoglobin, cytochrome P450, DGCR8, and nitric oxide synthase, among others. This protocol describes a method for quantifying heme that works best in purified protein samples. This protocol ...
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