Component of the signal recognition particle (SRP) complex, a ribonucleoprotein complex that mediates the cotranslational targeting of secretory and membrane proteins to the endoplasmic reticulum (ER) (By similarity). The SRP complex interacts with the signal sequence in nascent secretory and membrane proteins and directs them to the membrane of the ER (By similarity). The SRP complex targets the ribosome-nascent chain complex to the SRP receptor (SR), which is anchored in the ER, where SR compaction and GTPase rearrangement drive cotranslational protein translocation into the ER (By similarity). Binds the signal recognition particle RNA (7SL RNA), srpa-72 binds to this complex subsequently (By similarity). The SRP complex possibly participates in the elongation arrest function (By similarity). Heterodimer with srpa-72 (By similarity). Srpa-68/srpa-72 heterodimer formation is stabilized by the presence of 7SL RNA (By similarity). Component of a signal recognition particle (SRP) complex that consists of a 7SL RNA molecule of 300 nucleotides and six protein subunits: srpa-72, srpa-68, SRP54, F37F2.2/SRP19, F25G6.8/SRP14 and ZK512.4/SRP9 (By similarity). Within the SRP complex, interacts (via C-terminus) with srpa-72 (via N-terminus) (By similarity). The N-terminus is required for RNA-binding. Belongs to the SRP68 family.