title: Intracellular processing of metalloprotease disintegrin ADAM12.
abstract: ADAM12 has been implicated in cell-cell interactions in myogenesis and cancer, but the structure of the mature form of ADAM12 is not known, and its localization on the cell surface has been questioned. In this report, we show that full-length ADAM12 is N-glycosylated in the endoplasmic reticulum (ER) and proteolytically processed in the trans-Golgi network to an approximately 90-kDa form. The approximately 90-kDa form, which lacks the prodomain, was the predominant form present at the cell surface. Replacement of Leu(73) in the putative alpha-helical region in the prodomain with proline resulted in retention of ADAM12 in the ER and a complete lack of its processing. However, deletion of the entire pro- and metalloprotease domains did not affect the processing and trafficking of ADAM12. In contrast, replacement of the cytoplasmic domain of ADAM12 with that of ADAM9 or adding a c-Myc tag at the C terminus led to a significant increase in transport of the protein to the cell surface. These results suggest that the cytoplasmic domain of ADAM12 plays an important role in regulating ADAM12 exit from the ER. We conclude that properly folded mouse ADAM12, after passing a rate-limiting step of exit from the ER, is processed in the secretory pathway and reaches the cell surface, where it can mediate adhesion-mediated signaling.
authors: Department of Biochemistry, Kansas State University, Manhattan, Kansas 66506, USA.
authors: Yi
authors: Y
authors: Cao
authors: Qing
authors: Q
authors: Kang
authors: Zhefeng
authors: Z
authors: Zhao
authors: Anna
authors: A
authors: Zolkiewska
mesh_terms: D051722:ADAM Proteins; D000072199:ADAM12 Protein; D000595:Amino Acid Sequence; D000818:Animals; D002448:Cell Adhesion; D002462:Cell Membrane / Q000378:metabolism; D019483:Disintegrins / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D017510:Protein Folding; D011817:Rabbits; D015398:Signal Transduction
chemical_list: D019483:Disintegrins; D008565:Membrane Proteins; D051722:ADAM Proteins; D000072199:ADAM12 Protein; C000606480:ADAM12 protein, human; C098339:ADAM9 protein, human; C498316:Adam9 protein, mouse; D008666:Metalloendopeptidases