Fig. 1

Schematic of PD-1/PD-L1 proteins highlighting potential PTM sites on PD-1/PD-L1. a The full-length PD-1 protein is divided into three segments: the ectodomain, transmembrane (TM), and a cytoplasmic region (CR). The ectodomain comprises the signal peptide (SP), N-loop, IgV domain, and stalk region, with amino acid positions denoted by numbers. Potential N-glycosylation sites at N49, N58, N74, and N116 are marked with blue arrowheads. Yellow arrowheads indicate potential tyrosine phosphorylation sites at Y223 and Y248. The poly-ubiquitination site at K48 is denoted by pink arrowheads. O-glycosylation sites at T153, S157, S159, and T168 are indicated with red arrows. b Full-length PD-L1 is divided into an ectodomain, transmembrane, and cytoplasmic region. The ectodomain comprises the signal peptide, IgV, and IgC domains, with amino acid positions indicated by numbers. Potential N-glycosylation sites at N35, N192, N200, and N219 are marked with blue arrowheads. Serine/threonine phosphorylation sites, located at S176, T180, S184, S195, and T210, are denoted by orange arrowheads. The S-palmitoylation site at C272 is indicated with a purple arrowhead. The mono/multiubiquitination motif is situated in the IgV domain, while the polyubiquitination site is in the cytoplasmic region of PD-L1. The acetylation site K263 is highlighted with a red arrow. Methylation sites at K75, K89, K105, R113, K162, and R212 are indicated with yellow arrowheads