The C9 methyl group of retinal interacts with glycine-121 in rhodopsin.

MLA

Han, M., et al. “The C9 Methyl Group of Retinal Interacts with Glycine-121 in Rhodopsin.” Proceedings of the National Academy of Sciences of the United States of America, vol. 94, no. 25, Dec. 1997, pp. 13442–47. EBSCOhost, https://doi.org/10.1073/pnas.94.25.13442.

APA

Han, M., Groesbeek, M., Sakmar, T. P., & Smith, S. O. (1997). The C9 methyl group of retinal interacts with glycine-121 in rhodopsin. Proceedings of the National Academy of Sciences of the United States of America, 94(25), 13442–13447. https://doi.org/10.1073/pnas.94.25.13442

Chicago

Han, M, M Groesbeek, T P Sakmar, and S O Smith. 1997. “The C9 Methyl Group of Retinal Interacts with Glycine-121 in Rhodopsin.” Proceedings of the National Academy of Sciences of the United States of America 94 (25): 13442–47. doi:10.1073/pnas.94.25.13442.