The main function of vacuolar H(+)-ATPases in eukaryotic cells is to generate proton and electrochemical gradients across the membranes of the vacuolar system. The enzyme is composed of a catalytic sector with five subunits (A-E) and a membrane sector containing at least two subunits (a and c). We disrupted two genes of this enzyme, in yeast cells, one encoding a subunit of the membrane sector ...

In this study a previously undescribed 3 bp deletion, AAT1030-1032, in the factor XIII A subunit gene, has been detected in a Thai patient. The inframe deletion results in the translation of a factor XIII A subunit that lacks Asn344. This is the first inframe deletion to be identified in the factor XIII A subunit gene because six previously reported deletions have all caused frameshifts. The de...

Protein kinases catalyze the transfer of the terminal phosphate of ATP to a variety of acceptor proteins [ 11. It has been demonstrated that cyclic adenosine 3’, 5’-monophosphate (cyclic AMP) activates protein kinase (holoenzyme, RC) by forming a complex with the regulatory subunit (R) to release the catalytic subunit (C) in the active state [2,3]. In a previous communication from this laborato...

A hyperstable complex of the tetrameric MuA transposase with recombined DNA must be remodeled to allow subsequent DNA replication. ClpX, a AAA+ enzyme, fulfills this function by unfolding one transpososome subunit. Which MuA subunit is extracted, and how complex destabilization relates to establishment of the correct directionality (left to right) of Mu replication, is not known. Here, using al...

ADP-glucose pyrophosphorylase, a key enzyme involved in the biosynthesis of starch in higher plants, is composed of pairs of large (LS) and small subunits (SS). Its catalytic activity is activated by 3-phosphoglyceric acid (3-PGA) and inhibited by inorganic phosphate (Pi). Current evidence indicates that the two subunit types play distinct roles in enzyme function. The large subunit is involved...

DNA polymerase gamma, Pol gamma, is the key replicative enzyme in animal mitochondria. The Drosophila enzyme is a heterodimer comprising catalytic and accessory subunits of 125 kDa and 35 kDa, respectively. Both subunits have been cloned and characterized in a variety of model systems, and genetic mutants of the catalytic subunit were first identified in Drosophila, as chemically induced mutati...

Endocytosis of Na(+),K(+)-ATPase molecules in response to G protein-coupled receptor stimulation requires activation of class I(A) phosphoinositide-3 kinase (PI3K-I(A)) in a protein kinase C-dependent manner. In this paper, we report that PI3K-I(A), through its p85alpha subunit-SH3 domain, binds to a proline-rich region in the Na(+),K(+)-ATPase catalytic alpha subunit. This interaction is enhan...

We have purified and isolated cDNAs encoding the beta subunit of tomato fruit polygalacturonase isoenzyme 1 (PG1), a cell wall protein that associates with, and apparently regulates, the catalytic PG2 polypeptides. Expression of the beta subunit is fruit specific and temporally separated from the expression of PG2 during fruit development. The 37- to 39-kD beta subunit is encoded as a 69-kD pre...

Two critical steps controlling serine recombinase activity are the remodeling of dimers into the chemically active synaptic tetramer and the regulation of subunit rotation during DNA exchange. We identify a set of hydrophobic residues within the oligomerization helix that controls these steps by the Hin DNA invertase. Phe105 and Met109 insert into hydrophobic pockets within the catalytic domain...

Katanin is a heterodimeric microtubule-severing protein that is conserved among eukaryotes. Loss-of-function mutations in the Caenorhabditis elegans katanin catalytic subunit, MEI-1, cause specific defects in female meiotic spindles. To determine the relationship between katanin's microtubule-severing activity and its role in meiotic spindle formation, we analyzed the MEI-1(A338S) mutant. Unlik...