ECPAS (Ecm29 proteasome adaptor and scaffold) is a molecular adapter protein that binds to the 26S proteasome and functions as a critical regulator of proteasome assembly and cellular proteolysis. ECPAS mediates the dissociation of 26S holoenzymes into 20S catalytic and 19S regulatory subcomplexes in response to cellular stress, particularly glucose starvation and oxidative stress 1. This structural remodeling is essential for adapting global proteolysis to physiological needs, as loss of ECPAS impairs degradation of 20S-specific substrates including puromycylated polypeptides 1. Mechanistically, ECPAS interacts directly with proteasome subunits and appears to intrude on the 20S-19S interface, triggering disassembly through conformational changes 2. ECPAS is also required for endoplasmic reticulum stress responses and cell survival during glucose starvation 1. Clinically, elevated ECPAS levels correlate with glucose-deprived tumor microenvironments 1, and ECPAS expression was identified as part of a nine-protein biomarker signature with robust performance (AUC=0.990) for assessing systemic lupus erythematosus disease exacerbation in peripheral blood mononuclear cells 3. These findings establish ECPAS as a key stress-response regulator that couples proteasome dynamics to cellular metabolic and oxidative status.