Biomedical subjects

E G Allwood

Publications and source records attributed to E G Allwood.

3 recordsLinked to original sources

PubMed2001

Phosphorylation of plant actin-depolymerising factor by calmodulin-like domain protein kinase.

The actin-depolymerising factor (ADF)/cofilin group of proteins are stimulus-responsive actin-severing proteins, members of which are regulated by reversible phosphorylation. The phosphorylation site on the maize ADF, ZmADF3, is Ser-6 but the kinase responsible is unknown [Smertenko et al., Plant J. 14 (1998) 187-193]. We have partially purified the ADF kinase(s) and found it to be calcium-regulated and inhibited by N-(6-aminohexyl)-[(3)H]5-chloro-1-naphthalenesulphonamide. Immunoblotting reveals that calmodulin-like domain protein kinase(s) (CDPK) are enriched in the purified preparation and addition of anti-CDPK to in vitro phosphorylation assays results in the inhibition of ADF phosphorylation. These data strongly suggest that plant ADF is phosphorylated by CDPK(s), a class of protein kinases unique to plants and protozoa.

Actin Depolymerizing Factors↗

PubMed2001

Interaction of pollen-specific actin-depolymerizing factor with actin.

We have examined the interaction of recombinant lily pollen ADF, LlADF1, with actin and found that whilst it bound both G- and F-actin, it had a much smaller effect on the polymerization and depolymerization rate constants than the maize vegetative ADF, ZmADF3. An antiserum specific to pollen ADF, antipADF, was raised and used to localize pollen ADF in daffodil--a plant in which massive reorganizations of the actin cytoskeleton have been seen to occur as pollen enters and exits dormancy. We show, for the first time, an ADF decorating F-actin in cells that did not result from artificial increase in ADF concentration. In dehydrated pollen this ADF : actin array is replaced by actin : ADF rodlets and aggregates of actin, which presumably act as a storage form of actin during dormancy. In germinated pollen ADF has no specific localization, except when an adhesion is made at the tip where actin and ADF now co-localize. These activities of pollen ADF are discussed with reference to the activities of ZmADF3 and other members of the ADF/cofilin group of proteins.

Actin Depolymerizing Factors↗

PubMed1999

Phosphorylation of phenylalanine ammonia-lyase: evidence for a novel protein kinase and identification of the phosphorylated residue.

The site of phosphorylation of phenylalanine ammonia-lyase (PAL) has been identified as a threonine residue. A Ca(2+)-stimulated protein kinase of approximately 55 kDa has been partially purified from elicited cells. The kinase can phosphorylate a synthetic peptide derived from PAL and a recombinant poplar PAL. PAL phosphorylation was associated with a decrease in Vmax in agreement with the suggestion that protein phosphorylation is involved in marking PAL subunits for turnover. The phosphorylation site in French bean PAL is most likely Thr545 in the sequence VAKRTLTT (539-546). Conservation of the phosphorylation site in PAL from diverse species suggests that phosphorylation of PAL may be a ubiquitous regulatory mechanism in higher plants.

Amino Acid Sequence↗