What is the fine-grained topic of the following text: Our results show that actin related protein 2 (Arp2) is essential for survival, but that the Dictyostelium protein can be complemented by E. histolytica Arp2, despite the presence of an insertion of 16 amino acids in an otherwise highly conserved protein. Only return the topic.
The role and compatibility of actin related protein 2 (Arp2) in survival and protein conservation.