Part of the CASK/TBR1/TSPYL2 transcriptional complex which modulates gene expression in response to neuronal synaptic activity, probably by facilitating nucleosome assembly. May inhibit cell proliferation by inducing p53-dependent CDKN1A expression. Interacts with histones. Interacts with CASK. Part of a complex containing CASK, TBR1 and TSPYL2. Enriched in transcriptionally active regions of chromatin in neurons. Present at high levels in the pituitary gland and at moderate levels in adrenal gland, brain, testis and ovary. In brain, expressed both in mature neurons and progenitor cells (at protein level). Present widely throughout embryogenesis. Present in developing brain from 10.5 dpc to P7 (at protein level). By TGFB1 or serum in pituitary cell lines (at protein level). Phosphorylation at Thr-333 impairs function on cell proliferation. Synaptic activity down-regulates TSPYL2 protein levels by inducing rapid proteasomal degradation. Subject to X inactivation. Belongs to the nucleosome assembly protein (NAP) family.