Different combinations of domains give rise to the diverse range of proteins found in nature. The identification of domains that occur within proteins can therefore provide insights into their function. Pfam also generates higher-level groupings of related families, known as clans.A clan is a collection of Pfam-A entries which are related by similarity of sequence, structure or profile-HMM.ifferent combinations of domains give rise to the diverse range of proteins found in nature. The identification of domains that occur within proteins can therefore provide insights into their function. Pfam also generates higher-level groupings of related families, known as clans.