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 (By similarity). Interacts with histones. Interacts with CASK. Part of a complex containing CASK, TBR1 and TSPYL2 (By similarity). Enriched in transcriptionally active regions of chromatin in neurons. Ubiquitously expressed, with highest levels in testis, adrenal gland, cerebral cortex, ovary, skeletal muscle and spleen. Present in testis, adrenal gland, cerebral cortex and ovary (at protein level). By TGFB1 and all-trans retinoic acid in lung cells (at protein level). Phosphorylation at Ser-20 and/or Thr-340 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.