A PH domain within OCRL bridges clathrin-mediated membrane trafficking to phosphoinositide metabolism.
OCRL, whose mutations are responsible for Lowe syndrome and Dent disease, and INPP5B are two similar proteins comprising a central inositol 5-phosphatase domain followed by an ASH and a RhoGAP-like domain. Their divergent NH2-terminal portions remain uncharacterized. We show that the NH2-terminal region of OCRL, but not of INPP5B, binds clathrin heavy chain. OCRL, which in contrast to INPP5B visits late stage endocytic clathrin-coated pits, was earlier shown to contain another binding site for clathrin in its COOH-terminal region. NMR structure determination further reveals that despite their primary sequence dissimilarity, the NH2-terminal portions of both OCRL and INPP5B contain a PH domain. The novel clathrin-binding site in OCRL maps to an unusual clathrin-box motif located in a loop of the PH domain, whose mutations reduce recruitment efficiency of OCRL to coated pits. These findings suggest an evolutionary pressure for a specialized function of OCRL in bridging phosphoinositide metabolism to clathrin-dependent membrane trafficking.
Mao
Yuxin
Y
Department of Cell Biology, Howard Hughes Medical Institute, Yale University, New Haven, CT 06511, USA.
Balkin
Daniel M
DM
Zoncu
Roberto
R
Erdmann
Kai S
KS
Tomasini
Livia
L
Hu
Fenghua
F
Jin
Moonsoo M
MM
Hodsdon
Michael E
ME
De Camilli
Pietro
P
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002966:Clathrin / Q000737:chemistry / Q000378:metabolism*; D018699:Coated Vesicles / Q000378:metabolism / Q000648:ultrastructure; D004705:Endocytosis; D006367:HeLa Cells; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D019906:Nuclear Magnetic Resonance, Biomolecular; D010716:Phosphatidylinositols / Q000378:metabolism; D010743:Phospholipids; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D051381:Rats; D016415:Sequence Alignment; D000099182:Phosphoinositide 5-Phosphatases
D002966:Clathrin; D010716:Phosphatidylinositols; D010743:Phospholipids; D010744:Phosphoric Monoester Hydrolases; D000099182:Phosphoinositide 5-Phosphatases; C075695:OCRL protein, human