We have identified a mouse full-length cDNA and gene encoding a novel protein (M-LP), based on an expressed sequence tag (EST) sequence (GenBank Accession No. AI482564) obtained by differential display screening of age-dependently expressed genes in mouse kidney. The ML-P gene is composed of three exons, ranges over 5 kb on mouse chromosome 16B1-B2 and is expressed as two transcripts (1455 and 3058 bp), both of which include the same open-reading frame encoding 194 amino acids. M-LP is expressed mainly in kidney and spleen and shows age-dependent expression. M-LP has sequence homologies and membrane topologies very similar to the Mpv17 protein, a peroxisomal protein involved in the development of early-onset glomerulosclerosis. Search of the protein domain family database (ProDom) revealed that M-LP is a new member of the Mpv17 domain family (PD008400).