DNA replication complex GINS protein PSF1 is a protein that in humans is encoded by the GINS1 gene. The GINS complex plays an essential role in the initiation of DNA replication, and progression of DNA replication forks. GINS complex seems to bind preferentially to single-stranded DNA. GINS1 is essential for function. Component of the GINS complex which is a heterotetramer of GINS1, GINS2, GINS3 and GINS4. Forms a stable subcomplex with GINS4. GINS complex interacts with DNA primase in vitro.