RNA-binding proteins (RBPs) play critical roles in post-transcriptional gene regulation by interacting with RNAs to form ribonucleoprotein (RNP) complexes. These proteins influence RNA structure, stability, function, transport, and localization. Eukaryotic cells encode thousands of RBPs, each with unique RNA-binding and protein-protein interaction properties. The diversity of RBPs allows for the formation of numerous RNP complexes, each tailored to specific RNAs. This review focuses on RBPs that interact with pre-mRNAs and mRNAs, highlighting their roles in post-transcriptional gene regulation. RBPs are characterized by various RNA-binding domains, such as RBD, KH, RGG, Sm, DEAD/DEAH, zinc finger, dsRBD, cold-shock, PUF, and PAZ domains. These domains enable RBPs to recognize specific RNA sequences and regulate RNA processing, splicing, polyadenylation, transport, localization, translation, and turnover. RBPs also undergo post-translational modifications, such as phosphorylation, arginine methylation, and SUMOylation, which modulate their function and interactions. RBPs are involved in various processes, including alternative splicing, RNA modification, polyadenylation, mRNA export, localization, translation, and turnover. For example, alternative splicing is regulated by RBPs like Nova and TDP43, which influence the production of different mRNA isoforms. RNA editing, mediated by ADAR proteins, modifies RNA sequences and affects gene expression. Polyadenylation is regulated by RBPs such as PABPN1, which influences mRNA stability and nuclear transport. mRNA export is facilitated by RBPs like TAP/NXF1, which ensure only fully processed mRNAs are exported from the nucleus. RBPs also play a role in mRNA localization, ensuring that mRNAs are transported to the correct cellular compartments for protein synthesis. Translation is regulated by RBPs such as ZBP1, which can repress or enhance translation depending on cellular conditions. mRNA turnover is controlled by RBPs like ELAV/Hu proteins, which stabilize mRNAs and influence their translation. The assembly of RNPs involves complex interactions between RBPs and RNAs, as well as between RBPs themselves. Examples include the exon-junction complex (EJC) and the CPE-binding protein (CPEB) RNP, which are involved in mRNA processing and regulation. These complexes highlight the dynamic nature of RNP assembly and its importance in gene expression. Overall, RBPs are essential components of eukaryotic gene expression, influencing every aspect of RNA biology. Their diversity and functional versatility underscore their importance in maintaining cellular function and in the development of diseases associated with RNA processing defects.RNA-binding proteins (RBPs) play critical roles in post-transcriptional gene regulation by interacting with RNAs to form ribonucleoprotein (RNP) complexes. These proteins influence RNA structure, stability, function, transport, and localization. Eukaryotic cells encode thousands of RBPs, each with unique RNA-binding and protein-protein interaction properties. The diversity of RBPs allows for the formation of numerous RNP complexes, each tailored to specific RNAs. This review focuses on RBPs that interact with pre-mRNAs and mRNAs, highlighting their roles in post-transcriptional gene regulation. RBPs are characterized by various RNA-binding domains, such as RBD, KH, RGG, Sm, DEAD/DEAH, zinc finger, dsRBD, cold-shock, PUF, and PAZ domains. These domains enable RBPs to recognize specific RNA sequences and regulate RNA processing, splicing, polyadenylation, transport, localization, translation, and turnover. RBPs also undergo post-translational modifications, such as phosphorylation, arginine methylation, and SUMOylation, which modulate their function and interactions. RBPs are involved in various processes, including alternative splicing, RNA modification, polyadenylation, mRNA export, localization, translation, and turnover. For example, alternative splicing is regulated by RBPs like Nova and TDP43, which influence the production of different mRNA isoforms. RNA editing, mediated by ADAR proteins, modifies RNA sequences and affects gene expression. Polyadenylation is regulated by RBPs such as PABPN1, which influences mRNA stability and nuclear transport. mRNA export is facilitated by RBPs like TAP/NXF1, which ensure only fully processed mRNAs are exported from the nucleus. RBPs also play a role in mRNA localization, ensuring that mRNAs are transported to the correct cellular compartments for protein synthesis. Translation is regulated by RBPs such as ZBP1, which can repress or enhance translation depending on cellular conditions. mRNA turnover is controlled by RBPs like ELAV/Hu proteins, which stabilize mRNAs and influence their translation. The assembly of RNPs involves complex interactions between RBPs and RNAs, as well as between RBPs themselves. Examples include the exon-junction complex (EJC) and the CPE-binding protein (CPEB) RNP, which are involved in mRNA processing and regulation. These complexes highlight the dynamic nature of RNP assembly and its importance in gene expression. Overall, RBPs are essential components of eukaryotic gene expression, influencing every aspect of RNA biology. Their diversity and functional versatility underscore their importance in maintaining cellular function and in the development of diseases associated with RNA processing defects.