Differential biochemical features of SIRPβ2 detected by mAbs LSB2.20 and 148. LSB2.20 immunoprecipitates from BW-SIRPβ2 transfectants and Jurkat-CD47⁰ reveal a broad cluster of approximately 45- to 50-kDa proteins, which may correspond to differentially glycosylated isoforms of SIRPβ2. Moreover, LSB2.20 immunoprecipitates include a 30-kDa protein, which may correspond to the alternatively spliced form of SIRPβ2, which lacks the membrane-proximal immunoglobulin domain and contains only one site for N-linked glycosylation (NCBI accession nos. AY748247 and AY748248). In contrast, the 148 immunoprecipitate from BW-SIRPβ2 cells reveals only a 50-kDa protein.