SRP68 is a core component of the signal recognition particle (SRP), a ribonucleoprotein complex essential for cotranslational protein targeting to the endoplasmic reticulum 1. SRP68 forms a functional heterodimer with SRP72 through interaction involving approximately 94 amino acids at its C-terminus, while its N-terminal region (residues 52-252) binds the SRP RNA (7SL RNA) 2. The SRP68/72 heterodimer recognizes signal sequences in nascent secretory and membrane proteins, directing the ribosome-nascent chain complex to the ER membrane where protein translocation occurs 1. Structurally, SRP68 interacts with SRP72's tetratricopeptide repeat domain through an unusually hydrophobic and extended surface 3. Recent cryo-EM analysis reveals that the SRP68/72 dimerization domain functions as both a protein- and RNA-binding interface, dynamically remodeling the SRP RNA and regulating elongation arrest upon ER docking 4. Beyond canonical SRP functions, SRP68/72 heterodimers possess a novel chr17-regulatory function, binding histone H4 tails in a manner inhibited by H4R3 methylation and activating transcription 5. Mutations in SRP68 disrupt its interaction with SRP72 and cause severe congenital neutropenia, highlighting its clinical significance in hematopoietic differentiation 3.