Before revision:  In this review, we introduce the steps required to collect protein data, train machine-learning models, and use trained models to guide engineering. We make recommendations at each stage and look to future opportunities for machine learning to enable the discovery of new protein functions and uncover the relationship between protein sequence and function.
After revision:  We then provide two case studies that demonstrate the ML-guided directed evolution process. We also look to future opportunities for machine learning to enable the discovery of new protein functions and uncover the relationship between protein sequence and function.