Structure of the adaptor protein p14 reveals a profilin-like fold with distinct function.
The adaptor protein p14 is associated with the cytoplasmic face of late endosomes that is involved in cell-surface receptor endocytosis and it also directly interacts with MP1, a scaffolding protein that binds the MAP kinase ERK1 and its upstream kinase activator MEK1. The interaction of p14 with MP1 recruits the latter to late endosomes and the endosomal localization of p14/MP1-MEK1-ERK1 scaffolding complex is required for signaling via ERK MAP kinase in an efficient and specific manner upon receptor stimulation. Here, we report the three-dimensional solution structure of the adaptor protein p14. The structure reveals a profilin-like fold with a central five-stranded beta-sheet sandwiched between alpha-helices. Unlike profilin, however, p14 exhibits weak interaction with selective phosphoinositides but no affinity towards proline-rich sequences. Structural comparison between profilin and p14 reveals the molecular basis for the differences in these functions. We further mapped the MP1 binding sites on p14 by NMR, and discuss the implications of these important findings on the possible function of p14.
Qian
Chengmin
C
Structural Biology Program, Department of Physiology and Biophysics, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA.
Zhang
Qiang
Q
Wang
Xueqi
X
Zeng
Lei
L
Farooq
Amjad
A
Zhou
Ming-Ming
MM
D033942:Adaptor Proteins, Vesicular Transport / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D003285:Contractile Proteins / Q000737:chemistry*; D011992:Endosomes / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology; D051379:Mice; D008840:Microfilament Proteins / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010743:Phospholipids / Q000378:metabolism; D011257:Pregnancy Proteins; D051304:Profilins; D011392:Proline / Q000378:metabolism; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
D033942:Adaptor Proteins, Vesicular Transport; D003285:Contractile Proteins; D008840:Microfilament Proteins; C495738:PFN1 protein, human; C495739:Pfn1 protein, mouse; D010743:Phospholipids; D011257:Pregnancy Proteins; D051304:Profilins; D011993:Recombinant Fusion Proteins; C043219:membrane-associated placental tissue protein 1; D011392:Proline