Phycocyanin There are 2 extra helices not found in normal globins (in red). The yellow group is similar to a heme. This is a bacterial or plant protein involved in photosynthesis. Brejc, K., Ficner, R., Huber, R., Steinbacher, S.: Isolation, crystallization, crystal structure analysis and refinement of allophycocyanin from the cyanobacterium Spirulina platensis at 2.3 A resolution. J Mol Biol 249 pp. 424 (1995) (PubMed) 1all (PDB)