Pfam数据库中，提供了以下3个不同层级蛋白质家族信息。
1.family（每个family以PF编号唯一标识，所有的family可以分为以下6种类型）：
- Family A collection of related protein regions
- Domain A structural unit
- Repeat A short unit which is unstable in isolation but forms a stable structure when multiple copies are present
- Motifs A short unit found outside globular domains
- Coiled-Coil Regions that predominantly contain coiled-coil motifs, regions that typically contain alpha-helices that are coiled together in bundles of 2-7.
- Disordered Regions that are conserved, yet are either shown or predicted to contain bias sequence composition and/or are intrinsically disordered (non-globular).
clan
对多个family进行相似性分析，将具有相似的三维结构或者相同motif的family归为一个clan, 可以看做是superfamily的概念，每个clan以CL编号标识，示意如下proteones
物种的蛋白质组信息，就是该物种内所有的蛋白质family 信息.
