Peptidylprolyl Isomerase Like Protein 5 (PPIL5)

Using the cytoplasmic domain of 4-1BB (TNFRSF9) as bait in a yeast 2-hybrid screen of a T-lymphoblastic leukemia cell line cDNA library, followed by screening a Jurkat T-cell cDNA library, Jang et al. (2001) cloned PPIL5, which they designated LRR1. The deduced 414-amino acid protein contains 8 tandem leucine-rich motifs, 2 potential N-glycosylation sites, and 2 N-myristylation sites. Jang et al. (2001) also identified an alternately spliced variant that encodes a protein lacking the leucine-rich region. Northern blot analysis detected transcripts of about 1.6 and 0.9 kb in all tissues and tumor cell lines examined. In normal tissues, highest expression was in heart and skeletal muscle, and lowest expression was in kidney.In addition, PPIL5 downregulated JNK1 (MAPK8) activation by 4-1BB.