Distribution of a major lysosomal membrane glycoprotein, LGP85/LIMP II, in rat tissues

We previously identified and characterized a major lysosomal membrane glycoprotein, termed LGP85 (identical to LIMP II), in rat liver lysosomes. This study describes the distribution of the mRNA and protein of LGP85 in rat tissues. LGP85 protein and mRNA were detectable in all tissues when analyzed by Western and Northern blotting. The 4.2- and 2.2-kb transcripts of LGP85 were detected in all tissues. Liver and lung have the highest and lowest levels of LGP85 mRNA, respectively. A single protein band with an apparent molecular weight (Mr) of approximately 85000 was detected in each tissue. The specific protein content of LGP85 in spleen was markedly higher than in other tissues. LGP85 protein is distributed in the tissues independently of LGP85 mRNA. Furthermore, there was a less significant relationship between LGP85 protein and another lysosomal membrane glycoprotein, lamp-1, in the tissue distribution (a regression coefficient of 0.086), which suggests that LGP85 may function in vivo independently of lamp-1.