STN1

OBFC1 (oligonucleotide/oligosaccharide-binding fold containing 1) is one of subunit of an alpha accessory factor (AAF) that stimulates the activity of DNA polymerase-alpha-primase, the enzyme that initiates DNA replication. OBFC1 also appears to function in a telomere-associated complex with C17ORF68 and TEN1.

Full Name

STN1, CST complex subunit

Function

Component of the CST complex proposed to act as a specialized replication factor promoting DNA replication under conditions of replication stress or natural replication barriers such as the telomere duplex. The CST complex binds single-stranded DNA with high affinity in a sequence-independent manner, while isolated subunits bind DNA with low affinity by themselves. Initially the CST complex has been proposed to protect telomeres from DNA degradation (PubMed:19854130).
However, the CST complex has been shown to be involved in several aspects of telomere replication. The CST complex inhibits telomerase and is involved in telomere length homeostasis; it is proposed to bind to newly telomerase-synthesized 3' overhangs and to terminate telomerase action implicating the association with the ACD:POT1 complex thus interfering with its telomerase stimulation activity. The CST complex is also proposed to be involved in fill-in synthesis of the telomeric C-strand probably implicating recruitment and activation of DNA polymerase alpha (PubMed:22964711, PubMed:22763445).
The CST complex facilitates recovery from many forms of exogenous DNA damage; seems to be involved in the re-initiation of DNA replication at repaired forks and/or dormant origins (PubMed:25483097).
Required for efficicient replication of the duplex region of the telomere. Promotes efficient replication of lagging-strand telomeres (PubMed:22863775, PubMed:22964711).
Promotes general replication start following replication-fork stalling implicating new origin firing (PubMed:22863775).
May be in involved in C-strand fill-in during late S/G2 phase independent of its role in telomere duplex replication (PubMed:23142664).
Component of the CST complex, a complex that binds to single-stranded DNA and is required to protect telomeres from DNA degradation. The CST complex binds single-stranded DNA with high affinity in a sequence-independent manner, while isolated subunits bind DNA with low affinity by themselves. In addition to telomere protection, the CST complex has probably a more general role in DNA metabolism at non-telomeric sites.

Biological Process

Biological Process negative regulation of telomere maintenance via telomeraseManual Assertion Based On ExperimentIDA:BHF-UCL
Biological Process positive regulation of DNA replicationISS:UniProtKB
Biological Process telomere cappingManual Assertion Based On ExperimentTAS:BHF-UCL
Biological Process telomere maintenanceManual Assertion Based On ExperimentIMP:UniProtKB
Biological Process telomere maintenance via telomere lengtheningManual Assertion Based On ExperimentIMP:UniProtKB

Cellular Location

Nucleus
Chromosome, telomere

Involvement in disease

Cerebroretinal microangiopathy with calcifications and cysts 2 (CRMCC2):
An autosomal recessive, multisystemic disorder characterized by intrauterine growth retardation and, later in life, premature aging symptoms, including poor growth, graying hair, liver fibrosis, portal hypertension, esophageal varices, osteopenia, pancytopenia, hypocellular bone marrow, and vascular telangiectasia resulting in gastrointestinal bleeding. Brain calcifications and white matter changes are responsible for signs including spasticity, ataxia, or dystonia observed in some patients.