Fold: Cyclin-like

core: 5 helices; one helix is surrounded by the others

Lineage:

1. Root: scop
2. Class: All alpha proteins
3. Fold: Cyclin-like
   core: 5 helices; one helix is surrounded by the others

Superfamilies:

1. Cyclin-like (3)
   duplication: consists of two domains of this fold
   1. Cyclin (6)
   2. Transcription factor IIB (TFIIB), core domain (2)
   3. Retinoblastoma tumor suppressor domains (1)