Requirement for p115 at a pre-Golgi VTC stage

ALVAREZ, C; FUJITA, H; HUBBARD, A; SZTUL, E

JOURNAL OF CELL BIOLOGY

ROCKEFELLER UNIV PRESS

Lugar: New York; Año: 1999 vol. 147 p. 1205 - 1222

0021-9525

The membrane transport factor p115 functionsin the secretory pathway of mammalian cells. Usingbiochemical and morphological approaches, weshow that p115 participates in the assembly and maintenanceof normal Golgi structure and is required for ERto Golgi traffic at a pre-Golgi stage. Injection of antibodiesagainst p115 into intact WIF-B cells causedGolgi disruption and inhibited Golgi complex reassemblyafter BFA treatment and wash-out. Addition ofanti?p115 antibodies or depletion of p115 from aVSVtsO45 based semi-intact cell transport assay inhibitedtransport. The inhibition occurred after VSV glycoprotein(VSV-G) exit from the ER but before its deliveryto the Golgi complex, and resulted in VSV-Gprotein accumulating in peripheral vesicular tubularclusters (VTCs). The p115-requiring step of transportfollowed the rab1-requiring step and preceded theCa21-requiring step. Unexpectedly, mannosidase I redistributedfrom the Golgi complex to colocalize withVSV-G protein arrested in pre-Golgi VTCs by p115 depletion.Redistribution of mannosidase I was also observedin cells incubated at 158C. Our data show thatp115 is essential for the translocation of pre-GolgiVTCs from peripheral sites to the Golgi stack. This definesa previously uncharacterized function for p115 atthe VTC stage of ER to Golgi traffic.