Complete sequence and transcript regulation of a cell adhesion protein from aggregating Dictyostelium cells

Abstract

Three cDNA clones coding for the contact site A (csA) protein, a cell adhesion molecule of Dictyostelium discoideum, were isolated by screening a cDNA library with monoclonal antibodies. Two of these clones contained the complete coding region for the csA protein of 1542 bp including a sequence of 57 bp coding for the leader. The N terminus of the mature protein, as it was published previously, was identified in the amino acid sequence derived from both full‐length cDNA clones. Southern blot analysis suggests the presence of only one csA gene in the haploid genome. Accumulation of the csA‐specific message of 1.9 kb begins during development on nitrocellulose filters at 9 h of starvation, and reaches a maximum at 12 h, the time of cell aggregation. Expression of the csA glycoprotein follows closely accumulation of the transcripts. In the multicellular slug stage following cell aggregation, the amount of csA transcripts rapidly declines to low levels.

cAMP‐dependent protein kinase activity is essential for preaggregative gene expression in Dictyostelium

“…We tested whether the defect in cAMP relay was due to reduced expression of ACA and other early and aggregative genes, mRNA was isolated during the first 8 h of starvation of representative R M and R c clones and hybridized to an A CA DNA probe [15] and to DNA probes for a number of other genes expressed after the onset of starvation, such as the early gene discoidin L that is induced by cell density sensing factors and repressed by cAMP [16][17][18], and the aggregative genes encoding cAMP-phosphodiesterase (PDE) [19], adhesive contact sites A (csA) [20] and the cAMP receptor cAR1 [21]. The aggregative genes are expressed at a low level in response to cell density sensing factors and to a high level by stimulation with cAMP pulses [22].…”

Evidence for a glycolipid anchor of gp64, a putative cell‐cell adhesion protein of Polysphondylium pallidum

“…A peak at mlz 561 is probably derived from a component whose methy group of the trimethylsilyl moiety was removed from phytosphingosine derivatives with molecular mass 575 and a proton was added. A large peak was also observed at mlz 174. site for glycolipid-anchor addition (Noegel et al, 1986). We have previously determined that the real C-terminal amino acid of gp64 is the first serine residue in the SSATT sequence (Manabe et al, 1994), although we still do not know the Cterminus of the contact-site-A glycoprotein.…”

A developmentally regulated gene product from Dictyostelium discoideum shows high homology to human α‐L‐fucosidase

“…For comparison, mRNA for the contact site A protein was labeled. This strictly regulated mRNA is known to be expressed shortly before the onset of aggregation, and to decay later during development [2]. The amount of contact site A mRNA peaked at 12 h of development, at the same time as the AllH2 mRNA ( fig.4).…”