The function of KCNN1 (potassium calcium-activated channel subfamily N member 1, Ensembl gene identifier ENSG00000105642) is as follows. Small conductance calcium-activated potassium channel that mediates the voltage-independent transmembrane transfer of potassium across the cell membrane through a constitutive interaction with calmodulin which binds the intracellular calcium allowing its opening (PubMed:17142458, PubMed:8781233, PubMed:9287325). The current is characterized by a voltage-independent activation, an intracellular calcium concentration increase-dependent activation and a single- channel conductance of about 3 picosiemens (PubMed:8781233). Also presents an inwardly rectifying current, thus reducing its already small outward conductance of potassium ions, which is particularly the case when the membrane potential displays positive values, above + 20 mV (Probable). Activation is followed by membrane hyperpolarization (By similarity). Thought to regulate neuronal excitability by contributing to the slow component of synaptic afterhyperpolarization (By similarity). {ECO:0000250|UniProtKB:Q9EQR3, ECO:0000269|PubMed:17142458, ECO:0000269|PubMed:8781233, ECO:0000269|PubMed:9287325, ECO:0000305|PubMed:9287325}.