I have an appreciable amount of interest in learning about the great molecular scissors, Cas proteins. Here are the list of useful Cas variants.
- xCas9, featured here on Addgene blog.The cool parts about this xCas9: (1) directed mutagenesis to generate this xCas9 was done via phage-assisted continuous evolution (PACE), and (2) it can recognize a broad range of PAM sites.
- GeoCas9, featured here on Addgene blog. As you might've guessed from its name, GeoCas9 is a thermostable Cas9 protein. Why this is useful? It can work better in human plasma than SpyCas9.
- Cpf1, featured here on Addgene blog. By comparing Cpf1 vs. typical Cas9, Cpf1 is better because it may improve HDR frequency, only requires crRNA (no tracrRNA requirement), and easier to deliver in low-capacity vectors (e.g. AAV vectors).