A Caps-Ubi Model for Protein Ubiquitination Site Prediction.

Ubiquitination, a widespread mechanism of regulating cellular responses in plants, is one of the most important post-translational modifications of proteins in many biological processes and is involved in the regulation of plant disease resistance responses. Predicting ubiquitination is an important technical method for plant protection. Traditional ubiquitination site determination methods are costly and time-consuming, while computational-based prediction methods can accurately and efficiently predict ubiquitination sites. At present, capsule networks and deep learning are used alone for prediction, and the effect is not obvious. The capsule network reflects the spatial position relationship of the internal features of the neural network, but it cannot identify long-distance dependencies or focus on amino acids in protein sequences or their degree of importance. In this study, we investigated the use of convolutional neural networks and capsule networks in deep learning to design a novel model "Caps-Ubi," first using the one-hot and amino acid continuous type hybrid encoding method to characterize ubiquitination sites. The sequence patterns, the dependencies between the encoded protein sequences and the important amino acids in the captured sequences, were then focused on the importance of amino acids in the sequences through the proposed Caps-Ubi model and used for multispecies ubiquitination site prediction. Through relevant experiments, the proposed Caps-Ubi method is superior to other similar methods in predicting ubiquitination sites.