A cDNA Encoding the Endoplasmic Reticulum-Luminal Heat-Shock Protein from Spinach (Spinacia oleracea L.)

The Phosphorylation State and Expression of Soybean BiP Isoforms Are Differentially Regulated following Abiotic Stresses

“…Collectively, these results may indicate that induction of soybean BiP in response to water stress occurs by a nonlinear or distinct pathway from that regulating the BiP response to the accumulation of unfolded proteins in the ER. and protein have been observed in spinach and soybean plants under specific stress conditions or developmental stages (13,25). These observations suggest that post-transcriptional mechanisms and/or differential expression of plant BiP gene family are involved in regulation of BiP synthesis in plants.…”

“…In water-stressed leaves, BiP synthesis is up-regulated to the same extent as in nutritionally stressed leaves and in pathogen-infected leaves. However, the synthesis of spinach BiP, which is a product of a single gene, is unaffected by water stress (13). In fact, in spinach, water stress resulted in disappearance of the BiP mRNA, although the level of protein remained unaltered.…”

“…This idea is supported by the observation that, as in mammalian cells, overexpression of BiP in tobacco leaf protoplasts attenuates ER stress caused by tunicamycin and prevents activation of the unfolded protein response pathway (23,24). However, in some plant species, specific stress conditions and developmental events alter BiP mRNA and protein levels to different extents, suggesting that post-transcriptional mechanisms are also involved in the regulation of BiP synthesis in plants (13,25). Alternatively or additionally, these discrepancies between the level of BiP mRNA and protein may reflect differential expression and regulation of plant BiP gene families, since the genome of several plant species is represented by multiple BiP genes (25)(26)(27).…”

“…Because phosphorylation and ADP-ribosylation appear to be restricted to oligomeric forms of mammalian BiP that are not bound to nascent polypeptides, the monomeric, unmodified form of BiP is thought to be the biologically active species (12). In spinach, three forms of BiP, the 85-kDa monomer, a 280-kDa multimeric form, and a 650-kDa oligomeric form, have been described (13). However, only the oligomeric form of BiP is phosphorylated in vitro, suggesting that, like mammals, the level of functional plant BiP is regulated by post-translational modification.…”

Proteins isolated from lucerne roots by affinity chromatography with sugars analogous to Nod factor moieties

“…The sequences of one peptide each for P60 and P78 are shown in Figure 7. Scanning of data banks (Fasta Search Results) showed identity between the peptide of P78 and a motif of putative proteins deduced from the cDNA of the 70 kDa heat shock protein (HSP70) [25][26][27]. In contrast, the sequence of 13 residues of P60 had some similarity to ferric leghaemoglobin reductase (FLbR ; EC 1.6.2.6) of soybean [28] and dihydrolipoamide dehydrogenase (DLDH ; EC 1.8.1.4) of pea [29].…”