The Golgi-associated protein GRASP is required for unconventional protein secretion during development.
During Dictyostelium development, prespore cells secrete acyl-CoA binding protein (AcbA). Upon release, AcbA is processed to generate a peptide called spore differentiation factor-2 (SDF-2), which triggers terminal differentiation of spore cells. We have found that cells lacking Golgi reassembly stacking protein (GRASP), a protein attached peripherally to the cytoplasmic surface of Golgi membranes, fail to secrete AcbA and, thus, produce inviable spores. Surprisingly, AcbA lacks a signal sequence and is not secreted via the conventional secretory pathway (endoplasmic reticulum-Golgi-cell surface). GRASP is not required for conventional protein secretion, growth, and the viability of vegetative cells. Our findings reveal a physiological role of GRASP and provide a means to understand unconventional secretion and its role in development.
Kinseth
Matthew A
MA
Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
Anjard
Christophe
C
Fuller
Danny
D
Guizzunti
Gianni
G
Loomis
William F
WF
Malhotra
Vivek
V
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D004023:Dictyostelium / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism / Q000502:physiology*; D000077614:Golgi Matrix Proteins; D008565:Membrane Proteins / Q000502:physiology*; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000378:metabolism / Q000502:physiology*; D033761:Spores, Protozoan / Q000737:chemistry / Q000254:growth & development / Q000502:physiology
C122048:GORASP2 protein, human; D000077614:Golgi Matrix Proteins; D008565:Membrane Proteins; D015800:Protozoan Proteins; C120676:ACB protein, Dictyostelium; D000262:Adenylyl Cyclases