Functional characterization of human ADP-ribosylation factor like-1(ARL1) and its interacting proteins
Date Issued
2006
Date
2006
Author(s)
Huang, Hsiao-Chuan
DOI
en-US
Abstract
ADP-ribosylation factors (ARFs) and ARF-like proteins (ARLs) are members of the ARF family, which play essential roles in intracellular membrane trafficking. These proteins are regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) to cycle between active GTP-bound form and inactive GDP-bound form. ARLs are ~40–60 % identical to each other and to ARFs. Despite their high similarity to ARFs, only ARL1 has been shown to be involved in vesicular transport. ARL1 is localized in the Golgi complex and may participate in trans-Golgi network (TGN) to plasma membrane or endosome to TGN trafficking pathway. In the first part, we investigated the function of ARL1 by using constitutively active (Q71L) or inactive (T31N) ARL1. Discrepant with previous studies, we found that overexpressed ARL1Q71L specifically disperses Golgin-245 from Golgi apparatus. Over-expressed ARL1T31N disrupted trans-Golgi proteins but not cis/medial Golgi and endosome proteins. Moreover, VSVG transport was blocked in ARL1Q71L overexpressed but not in ARL1 knockdown cells which implied that ARL1 itself may not directly participate in the VSVG transport. In the second part, we attempted to find possible GAP for ARL1. Among our three candidates, ARFGAP1 did not interact with ARL1 in yeast two-hybrid assay but endogenous ARL1 were dissociated from the Golgi in cells with overexpressed ARFGAP1, which we considered an indirect consequence of general effect on Golgi proteins. Centaurin α1 neither interacted with ARL1 nor affected ARL1 localization. ARAP1 interacted with ARL1Q71LdN, but we could not detect the change of ARL1 localization when ARAP1 overexpressed. Whether ARAP1 could be GAP for ARL1 needs to be investigated further. In the third part, we identified an ARL1Q71L interacting protein, CIB1. We showed that ARL1 interacted with CIB1 in a Ca2+-dependent manner. Furthermore, CIB1 was ubiquitously expressed in cells especially colocalized with ARL1 in the Golgi apparatus in particular conditions. In addition, Golgi localization of CIB1 was not dependent on ARL1, and vice versa. Unfortunately, even though the interaction and colocalization of ARL1 and CIB1 were observed, we could not demonstrate the functional relevance between these two proteins.
Subjects
腺嘌呤核苷
二磷酸核醣化因子
ARF
ARL1
CIB1
GAP
Golgi
Type
other
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