c1D

c1D, typically written C1D, designates a gene encoding a nuclear DNA-binding protein found in many eukaryotes, including humans. The protein is relatively small and lacks catalytic activity, instead serving as a chromatin-associated factor involved in the cellular response to DNA damage. C1D binds to both single-stranded and double-stranded DNA in a sequence-independent manner, with a preference for damaged DNA ends, and it localizes to the nucleus where it can form discrete foci following DNA damage.

Expression of C1D is constitutive in many tissues, but several studies report upregulation in response to DNA-damaging agents such as ionizing radiation or replication stress, consistent with a role in damage signaling and repair. In cells, C1D interacts with components of the DNA damage response network and can influence chromatin organization at sites of damage, thereby facilitating repair processes. The precise molecular functions of C1D are still being investigated, but genetic and biochemical data support roles in maintaining genome stability and in modulating transcriptional programs linked to stress responses.

C1D is conserved across eukaryotes, with orthologs identified in a range of species, reflecting its fundamental role in DNA maintenance. Aberrant regulation of C1D expression or function has been examined in cancer biology and aging research, where genome instability is a common feature. Further studies aim to clarify its interactions, regulatory mechanisms, and potential as a biomarker or therapeutic target.