The small GTPase Rab4A interacts with the central region of cytoplasmic dynein light intermediate chain-1.
Rab4 belongs to the Rab family of small GTPases involved in the regulation of intracellular transport, and has been localized to early endosomes. We have employed the yeast two-hybrid system to identify proteins that specifically interact with Rab4AQ67L, a GTPase-deficient mutant form of Rab4A. Screening a mouse embryo cDNA library identified a clone (M449) that interacted with Rab4A in a nucleotide-dependent fashion. Data base searches identified this clone as the mouse cytoplasmic dynein light intermediate chain-1 (LIC-1). Based on this finding, the full-length equivalent human cytoplasmic dynein LIC-1 was isolated by PCR. When Rab4A was overexpressed together with either M449 or dynein LIC-1 in HeLa cells, the proteins were found to colocalize in the perinuclear region. We characterize the localization of both overexpressed human dynein LIC-1 and the endogenous protein with respect to microtubules and show that it concentrates to the microtubule-organizing center and mitotic spindle. Additionally, GFPRab4A endosomes localize to microtubules and are redistributed by nocodazole treatment. This is the first described interaction between cytoplasmic dynein, a retrograde motor protein, and a Rab protein.
Cell & Molecular Biology Laboratory, University College Cork, Ireland.
A
A
Bielli
P O
PO
Thörnqvist
A G
AG
Hendrick
R
R
Finn
K
K
Fitzgerald
M W
MW
McCaffrey
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D056445:Cytoplasmic Dyneins; D004398:Dyneins / Q000235:genetics* / Q000378:metabolism*; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism; D018922:HL-60 Cells; D006367:HeLa Cells; D006801:Humans; D019169:Jurkat Cells; D051379:Mice; D022101:Microtubule-Organizing Center / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D015739:Nocodazole / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D008941:Spindle Apparatus / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D020695:rab4 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
C424131:DYNC1LI1 protein, human; C486041:Dync1li1 protein, mouse; D056445:Cytoplasmic Dyneins; D004398:Dyneins; D020695:rab4 GTP-Binding Proteins; D015739:Nocodazole