Phospho-YAP (Ser61) Antibody recognizes endogenous levels of YAP protein only when phosphorylated at Ser61. This antibody does not cross-react with phosphorylated TAZ, due to the absence of an equivalent modification site in the TAZ protein.

Polyclonal antibodies are produced by immunizing animals with a synthetic phosphopeptide corresponding to residues surrounding Ser61 of human YAP protein. Antibodies are purified by peptide affinity chromatography.

YAP (Yes-associated protein, YAP65) was first identified based on its ability to associate with the SH3 domain of Yes. It also binds to other SH3 domain-containing proteins such as Nck, Crk, Src, and Abl (1). In addition to the SH3 binding motif, YAP contains a PDZ interaction motif, a coiled-coil domain, and WW domains (2-4). While initial studies of YAP all pointed towards a role in anchoring and targeting to specific subcellular compartments, subsequent studies showed that YAP is a transcriptional co-activator by virtue of its WW domain interacting with the PY motif (PPxY) of the transcription factor PEBP2 and other transcription factors (5). In its capacity as a transcriptional co-activator, YAP is now widely recognized as a central mediator of the Hippo Pathway, which plays a fundamental and widely conserved role in regulating tissue growth and organ size (6-8). Phosphorylation at multiple sites (e.g., Ser109, Ser127) by LATS kinases promotes YAP translocation from the nucleus to the cytoplasm, where it is sequestered through association with 14-3-3 proteins (7-9). These LATS-driven phosphorylation events serve to prime YAP for subsequent phosphorylation by CK1δ/ε in an adjacent phosphodegron, triggering proteasomal degradation of YAP (10).
YAP function is influenced by cellular metabolic status. This was recognized after observing that AMPK, a master regulator of cell metabolism, directly phosphorylates YAP at multiple sites (e.g., Ser61, Ser94) during energy stress or nutritional deprivation (11-13). Phosphorylation of Ser61 by AMPK did not increase 14-3-3 binding or affect YAP subcellular localization, but nevertheless resulted in transcriptional repression of YAP target genes (12).