Identification of N-glycosylation sites on AtERO1 and AtERO2 using a transient expression system

Arabidopsis PDI11 interacts with lectin molecular chaperons calreticulin 1 and 2 through its D domain

The endoplasmic reticulum (ER) is equipped with protein disulfide isomerases (PDIs), molecular chaperons, and other folding enzymes to ensure that newly synthesized proteins in the ER are properly folded. Molecular chaperons and PDIs can form complex to promote protein folding in the ER of mammalian cells. In plants, many PDIs associate with each other and function cooperatively in oxidative protein folding. As a plant unique protein disulfide isomerase, Arabidopsis thaliana PDI11 (AtPDI11) demonstrates oxidative protein folding activities and works synergistically with AtPDI2/5. However, whether AtPDI11 associates with molecular chaperons or AtPDIs in catalyzing disulfide formation remained unknown. Here, we find that AtPDI11 interacts with ER resident lectin chaperones calreticulin 1 (CRT1) and CRT2. Furthermore, the D domain, but not the a or a' domain of AtPDI11 provides the biding sites for its interaction with CRT1/2. Moreover, the P domain of CRT1 is responsible for its interaction with AtPDI11. Our work implies that Arabidopsis CRT1/2 may specifically recruit AtPDI11 to assist the folding of glycoproteins in the ER.

Emerging roles of N-linked glycosylation in brain physiology and disorders

N-linked glycosylation is a complex, co- and post-translational series of events that connects metabolism to signaling in almost all cells. Metabolic assembly of N-linked glycans spans multiple cellular compartments, and early N-linked glycan biosynthesis is a central mediator of protein folding and the unfolded protein response (UPR). In the brain, N-linked glycosylated proteins participate in a myriad of processes, from electrical gradients to neurotransmission. However, it is less clear how perturbations in N-linked glycosylation impact and even potentially drive aspects of neurological disorders. In this review, we discuss our current understanding of the metabolic origins of N-linked glycans in the brain, their role in modulating neuronal function, and how aberrant N-linked glycosylation can drive neurological disorders.

Role of Glycoproteins during Fruit Ripening and Seed Development

Approximately thirty percent of the proteins synthesized in animal or plant cells travel through the secretory pathway. Seventy to eighty percent of those proteins are glycosylated. Thus, glycosylation is an important protein modification that is related to many cellular processes, such as differentiation, recognition, development, signal transduction, and immune response. Additionally, glycosylation affects protein folding, solubility, stability, biogenesis, and activity. Specifically, in plants, glycosylation has recently been related to the fruit ripening process. This review aims to provide valuable information and discuss the available literature focused on three principal topics: (I) glycosylations as a key posttranslational modification in development in plants, (II) experimental and bioinformatics tools to analyze glycosylations, and (III) a literature review related to glycosylations in fruit ripening. Based on these three topics, we propose that it is necessary to increase the number of studies related to posttranslational modifications, specifically protein glycosylation because the specific role of glycosylation in the posttranslational process and how this process affects normal fruit development and ripening remain unclear to date.