A protein domain is a part of protein sequence and structure that can evolve, function, and exist independently of the rest of the protein chain. Each domain forms a compact three-dimensional structure and often can be independently stable and folded.

A protein kinase is a kinase enzyme that modifies other proteins by chemically adding phosphate groups to them (phosphorylation).

The average linkage clustering is a method of calculating distance between clusters. The linkage function specifying the distance between two clusters is computed as the average distance between objects from the first cluster and objects from the second cluster.

Manhattan distance is the method used to calculate distance between objects in a raster data layer by counting the distance along the sides of the raster cells.

The silhouette score measures whether a single data point is well clustered; it helps judging the overall quality of the clustering.