|Detection of Human LRMP by Western Blot. Western blot shows lysates of Ramos human Burkitt's lymphoma cell line and Daudi human Burkitt's lymphoma cell line. PVDF membrane was probed with 1 µg/mL of Sheep Anti-Human LRMP Antigen Affinity-purified Polyclonal Antibody (Catalog # AF6869) followed by HRP-conjugated Anti-Sheep IgG Secondary Antibody (Catalog # HAF016). A specific band was detected for LRMP at approximately 75 kDa (as indicated). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 1.|
LRMP (Lymphoid restricted membrane protein; also JAW1) is a 74-76 kDa protein that is associated with the ER. In contrast to its name, LRMP expression is not restricted to lymphoid cell types. Cells known to express LRMP include stomach chief cells, seminal vesicle cuboidal epithelium, neurons, germinal center B cells, cortical thymocytes, and cells of the taste buds. LRMP is suggested to participate in intracellular peptide transport. It is also reported to physically interact with IP3RP. Human LRMP is a 56 kDa (predicted), single-pass transmembrane (TM) protein that is 499 amino acids (aa) in length. It contains a 439 aa cytoplasmic region (aa 1-439), a 21 aa TM segment (aa 440-460) and a 39 aa luminal domain (aa 461-499) that is cleaved after Ala469 to generate a type IV TM protein. LRMP runs anomalously in SDS-Page, and the 75 kDa form may be linked to an isoform that utilizes a Leu start site 56 aa upstream of the start site for the 499 aa isoform. In this regard, a human isoform has been reported that is 62 kDa in size. Mature mouse LRMP is 509 aa in length (after cleavage) and runs at 65 kDa in SDS-PAGE. Over aa 143-292, human LRMP shares 93% aa identity with mouse LRMP.