Molecular And Biochemical Characterization Of GTP-bindin

adp -核糖基化因子结构域蛋白（ARD1）最初在本实验室克隆，与其他ARF不同，它具有46 kda的n端延伸（p5），其功能是c端ARF结构域（p3）的gtpase激活蛋白（GAP）。与ARF GAP蛋白一样，ARD1的GAP结构域包含锌指基序和精氨酸残基，这些残基对活性至关重要。它与其他ARF GAP的不同之处在于它与gtp结合域的共价结合以及它的GAP活性对ARD1的ARF结构域的特异性。一个假定的替代剪接mRNA和蛋白质产物的研究正在完成。据推测，arf在细胞内运输囊泡的形成及其从一个隔室到另一个隔室的运动中起关键作用。过表达和内源性ARD1都与高尔基体膜和溶酶体膜有关，与这些隔室之间的蛋白质运输作用一致。ARD1似乎可以被cytohesin-1特异性激活，并且鉴定出了与cytohesin-1/ARD1相互作用特异性相关的残基。在ARD1“敲除”小鼠中，由于反复回交后的繁殖问题而减慢的多种表型的表征再次进行。

ADP-ribosylation factor domain protein (ARD1) initially cloned in this laboratory, differs from other ARFs having a 46-kDa N-terminal extension (p5), which functions as a GTPase-activating protein (GAP) for the C-terminal ARF domain (p3). Like ARF GAP proteins, the GAP domain of ARD1 contains a zinc-finger motif and arginine residues that are critical for activity. It differs from other ARF GAPs in its covalent association with the GTP-binding domain and the specificity of its GAP activity for the ARF domain of ARD1. Study of a putative alternatively spliced mRNA and protein product is being completed. ARFs are presumed to play a key role in the formation of intracellular transport vesicles and their movement from one compartment to another. Both overexpressed and endogenous ARD1 were associated with Golgi and lysosomal membranes, consistent with a role in protein trafficking among these compartments. ARD1 appears to be activated specifically by cytohesin-1, and residues responsible for specificity of the cytohesin-1/ARD1 interaction were identified. Characterization of multiple phenotypes in ARD1 "knock-out" mice, which had been slowed by problems with reproduction after repeated back-crossing, is again proceeding.