The serine kinase protein kinase D (PKD) has a cysteine-rich domain (CRD) that binds diacylglycerol (DAG) with high affinity. PKD is cytosolic in unstimulated T cells, but it rapidly polarizes to the immunological synapse in response to antigen/antigen presenting cells (APCs). PKD repositioning is determined by the accumulation of DAG at the immunological synapse and changes in DAG accessibility of the PKD-CRD. Unstimulated T cells are shown to have a uniform distribution of DAG at the plasma membrane, whereas after T cell activation, a gradient of DAG is created with a persistent focus of DAG at the center of the synapse. PKD is only transiently associated with the immune synapse, indicating a fine tuning of PKD responsiveness to DAG by additional regulatory mechanisms. These results reveal the immune synapse as a focal point for DAG and PKD as an immediate and dynamic DAG effector during T cell activation.

The increasing use of peptides as pharmaceutical agents, especially in the antiviral and anti-infective therapeutic areas, requires cost-effective production on a large scale. Many peptides need carboxy amidation for full activity or prolonged bioavailability. However, this modification is not possible in prokaryotes and must be done using recombinant enzymes or by expression in transgenic milk. Methods employing recombinant enzymes are appropriate for small-scale production, whereas transgenic milk expression is suitable for making complex disulfide-containing peptides required in large quantity. Here we describe a method for making amidated peptides using a modified self-cleaving vacuolar membrane ATPase (VMA) intein expression system. This system is suitable for making amidated peptides at a laboratory scale using readily available constructs and reagents. Further improvements are possible, such as reducing the size of the intein to improve the peptide yields (the VMA intein comprises 454 amino acids) and, if necessary, secreting the fusion protein to ensure correct N-terminal processing to the peptide. With such developments, this method could form the basis of a large-scale cost-effective system for the bulk production of amidated peptides without the use of recombinant enzymes or the need to cleave fusion proteins.

No abstract

The somatic cell hybrid C121, with chromosome 7 as its sole human component, arose when mouse macrophages SV40 genomes are integrated at 7q31-7q35. We show that hybrids with a reduced chromosome 7 component, but which retain markers linked to the cystic fibrosis locus, can be generated by direct in vivo tumor selection or following chromosome-mediated gene transfer and SV40-mediated cellular transformation. Our methods for chromosome fragmentation and fine-structure mapping can now be applied to the substantial number of SV40-transformed human cell lines, with independent chromosomal integration sites, already available. Our results also suggest that expression of human epidermal growth factor receptor augments the tumorigenic potential of the SV40-transformed C121 hybrid.