## FAQ

SeQuery is an online graph database of biological networks, which was built based on our previous study. The graph database can be viewed via most popular browsers (such as Chrome, Firefox, Opera, Safari, Edge, and Internet Explorer) on a PC, Mac, or Linux. However, some graphical designs of the database might not work properly on mobile devices.

Currently SeQuery only contains the database of the GPCR network. In the future, more biological databases will be added to SeQuery.

The distance between sequences $$i$$ and $$j$$ is defined as $$D_{i,j} = \sqrt{E_{i,j}E_{j,i}},$$ where $$E_{i,j}$$ is their BLAST E value. (For more details, see the reference paper.)

In a 1st level graph, a cluster is made up of the most related GPCRs predicted by the MSC (Minimum Span Clustering) method (see the reference paper). A node in the 1st level graphs represents a GPCR sequence, and an edge represents the sequence distance between two nodes. The core of a cluster contains nodes whose mutual distances are the shortest in the graph. In the graphs, we use a segment for an edge of zero distance, a double-headed arrow for the shortest (non-zero) distance, and an arrow for all other edges (pointing towards the core).

The 2nd level network shows the MST (Minimum Spanning Tree) diagram of nodes, in which each node represents a 1st level MSC cluster. An edge between two nodes represents the shortest sequence distance between these two clusters.

The 3rd level network shows the MST (Minimum Spanning Tree) diagram of nodes, in which each node represents a GPCR family. An edge between two GPCR families is the shortest sequence distance between these two families.