[The double-play of PP17/TIP47].
A missing link in the understanding of the mechanisms of transport of the mannose 6-phosphate receptors has recently been discovered, following the identification of the protein TIP47. In association with Rab9-GTP, this protein is responsible for the return of the receptors from the late endosomes back to the trans-Golgi network. Curiously, the same protein called PP17b, was described as a placental protein twenty years ago, and more recently, as a blood marker for human uterine cervical cancer. The sequence of PP17b/TIP47 displays not only a strong homology with those of adipophilin and the perilipins, two proteins known to be involved in the intracellular traffic of lipid droplets but also PP17b/TIP47 is associated with the later. How this ubiquitous protein could participate in processes as different as the mannose 6-phosphate receptors traffic and the formation and/or traffic of lipid droplets? A tentative hypothesis is put forward.
Pauloin
Alain
A
Unité de Génomique et physiologie de la lactation, Inra, 78352 Jouy-en-Josas, France. pauloin@jouy.inra.fr
Ollivier-Bousquet
Michèle
M
Chanat
Eric
E
D000595:Amino Acid Sequence; D004268:DNA-Binding Proteins / Q000235:genetics / Q000494:pharmacology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000494:pharmacology*; D050356:Lipid Metabolism; D008969:Molecular Sequence Data; D000070796:Perilipin-3; D011257:Pregnancy Proteins / Q000235:genetics / Q000494:pharmacology*; D017527:Receptor, IGF Type 2 / Q000502:physiology*; D033921:Vesicular Transport Proteins
D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C038196:PLIN3 protein, human; D000070796:Perilipin-3; D011257:Pregnancy Proteins; D017527:Receptor, IGF Type 2; D033921:Vesicular Transport Proteins