The hypothesis has yet been proven, and PPDK’s role in the grain-filling remains to be further studied. The change in the concentration of the metabolites is thus used as an indicator for the biological process. Likewise, the dynamic changes of the protein expression during the grain development of rice reflected the progress of the glycolysis and TCA cycle, which peaked in EGS or MGS. The rice grains were filled from EGS to MGS going through the sink establishment in EGS by endosperm cell enlargement, and thereafter, the starch synthesis. Completion of the prominent glycolysis and TCA cycle in EGS and MGS require an adequate supply of ATP and the synthesis of cellular components Reversine essential for the cell enlargement and starch synthesis. In our study, the expression abundance of most of the identified proteins relating to the glycolysis and TCA cycle was found to be lower in the grains on IS than SS. The key glycolysis enzymes were downregulated during EGS and MGS, and those associated with the TCA cycle in MGS. The results suggested that the slowed glycolysis and TCA cycle in IS during EGS and MGS reduced the progress of the endosperm cell enlargement and starch synthesis, which were detrimental to the sink establishment in the grains. Three glycolysis proteins, phosphoglycerate mutase, phosphoglycerate kinase and enolase, were detected by means of Pro-Q Diamond staining. PGK was also identified in oilseed rape by the same staining method, and its phosphopeptide by LC-MS/MS/MS. PGAM phosphorylation was detected in arabidopsis seeds. And, the enolase was OTX015 phosphorylated on a single tyrosine. These enzymes encountered varied phosphorylation on SS and IS, indicating that the glycolysis in IS could be artificially altered through phosphorylation manipulation. Our earlier phosphoproteomic work showed that the addition of ABA could indeed change the phosphorylation of PGK and enolase in IS to promote the grain-filling. During LGS, the two key enzymes in alcohol fermentation, ADH and transketolase, were downregulated in IS. The fermentation is a two-step process that includes the branching from the glycolysis pathway at pyruvate with concomitant oxidization of NADH to NAD+, and then, the generating of ATP anaerobically. In a typical development of seeds or bulky organs, the internal oxygen concentration is greatly reduced. The upregulation of alcohol fermentation pathway is very important for maintaining an appropriate ATP level for the starch synthesis under low oxygen tension. They are capable of binding a multitude of functionally diverse signaling proteins, including kinases, phosphatases, and transmembrane receptors. A recent proteomic study on soybean and oilseeds also found the proteins highly expressed during the seed development with an involvement in the signaling and metabolic pathways. Furthermore, 14-3-3 are phosphopeptide-binding proteins with its phosphorylation detected in oilseed rape. However, no in vivo phosphorylation of the proteins in rice grains has been identified thus far. Stained with Pro-Q Diamond dye, 14-3-3 protein showed phosphorylation levels different between SS and IS.