Protein Kinase C and Casein Kinase Substrate in Neurons Protein 1 (PACSIN1) belongs to the PACSIN family. PACSIN1 contains one FCH domain and one SH3 domain. PACSIN1 is highly expressed in the brain and at lower leves in the heart, pancreas, and liver. PACSIN1 may play a role in vesicle formation and transport. PACSIN1 has been shown to interact with DNM1, PACSIN3, Huntingtin, and PACSIN2. In addition, PACSIN1 is phosphorylated by casein kinase 2 (CK2) and protein kinase C (PKC).