ADP-ribosylation factor (ARF)-like 3, a new member of the ARF family of GTP-binding proteins cloned from human and rat tissues.
The human and rat homologues of a new member of the ADP-ribosylation factor (ARF) family of 21-kDa GTP-binding proteins, termed Arl3, were identified as an expressed sequence tag (human) and as a product of polymerase chain reaction amplification using degenerate probes derived from conserved sequences in members of the ARF family (rat). Alignments of the full-length open reading frames of the human and rat homologues revealed the encoded proteins to be over 97% identical to each other and 43% identical to human ARF1. Northern blots of mRNA from seven human tissues and four rat tissues revealed the presence of a ubiquitous band of about 1 kilobase in length that hybridized with the corresponding Arl3 probes. A number of human tumor cell lines expressed Arl3, as determined by immunoblotting with an Arl-specific antibody, raised against a peptide derived from the human Arl3 sequence. The level of Arl3 expressed in these cell lines was on the order of 0.01% of total cell protein. Purified recombinant human Arl3 was shown to bind guanine nucleotides but lacks ARF activity and intrinsic or ARF GTPase-activating protein-stimulated GTPase activity. In contrast to ARF proteins, the Arl3 protein has reduced dependence on phospholipids and magnesium for guanine nucleotide exchange. Thus, Arl3 is a ubiquitously expressed GTP-binding protein in the ARF family with distinctive biochemical properties consistent with its having unique, but unknown, role(s) in cell physiology.
Cavenagh
M M
MM
Laboratory of Biological Chemistry, NCI, National Institutes of Health, Bethesda, Maryland 20892.
Breiner
M
M
Schurmann
A
A
Rosenwald
A G
AG
Terui
T
T
Zhang
C
C
Randazzo
P A
PA
Adams
M
M
Joost
H G
HG
Kahn
R A
RA
D020823:ADP-Ribosylation Factor 1; D020727:ADP-Ribosylation Factors; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D019204:GTP-Binding Proteins / Q000235:genetics*; D015870:Gene Expression; D006801:Humans; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011994:Recombinant Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D012333:RNA, Messenger; D011994:Recombinant Proteins; D019204:GTP-Binding Proteins; D020823:ADP-Ribosylation Factor 1; D020727:ADP-Ribosylation Factors; C490247:ARL3 protein, human; C088389:Arl3 protein, rat