Calcyclin-binding protein

Calcyclin-binding protein (CACYBP) is a 228-amino acid protein that functions as a molecular bridge in ubiquitin E3 ligase complexes, facilitating calcium-dependent ubiquitination and proteasomal degradation of target proteins (UniProt: Q9HB71). It participates notably in the ubiquitin-mediated degradation of β-catenin, linking calcium signaling to protein homeostasis pathways that regulate cell adhesion and Wnt signaling.

CACYBP is expressed in human tissues and its regulatory role in ubiquitin-proteasome system function positions it within broader cellular quality control mechanisms (UniProt: Q9HB71). The protein has no established monogenic disease associations in UniProt curated data.

CACYBP shows elevated abundance in Alzheimer's Disease pathology. Quantitative proteomics of human post-mortem AD brain tissue versus age-matched controls detected CACYBP upregulation with a mean log2 fold-change of 0.4967 across subcellular fractions (Chaparral AD proteomics). This increase may reflect compensatory or pathological enhancement of ubiquitin-mediated protein degradation in response to AD-associated protein aggregation and proteostasis dysfunction.