Table 1.

RNA-binding domains and protein engineering attempts.

RBD	Engineered?	Size (Amino Acids)	RNA Target	Representative References
RRM	Yes	85	ssRNA, Stem-loop RNA	(Laird-Offringa and Belasco 1995)
dsRBD	Yes	68	dsRNA (A-form), Stem-loop	(Lee, Cho et al. 2010)
PUF	Yes	36	ssRNA	(Wang, Wang et al. 2013)
Zinc Fingers	Yes	30	ssRNA, dsRNA, Stem Loop RNA, Tertiary folded RNA	(Hale, Richardson et al. 2018, De Franco, Vandenameele et al. 2019)
KH	No	70	ssRNA	(Garrey, Cass et al. 2008, Hollingworth, Candel et al. 2012)
RGG	Yes	8–17	RNA G-quartet	(Takahama, Miyawaki et al. 2015)
PPR	Yes	35	ssRNA	(Barkan, Rojas et al. 2012, Okuda, Shoki et al. 2014, Kindgren, Yap et al. 2015, Miranda, Rojas et al. 2017)