With　the　ongoing　expansion　of　user　numbers　and　the　diversity　of　business　types,　wireless　networks　are　progressing　toward　broader　spatial　dimensions　and　increased　functionality.　With　respect　to　coverage,　the　space-air-ground　integrated　network　(SAGIN)　is　considered　a　promising　solution　for　providing　seamless　global　connectivity　to　emerging　services.　In　terms　of　functionality,　wireless　networks　are　expected　to　offer　not　only　communication　services　but　also　sensing　and　computing　services,　which　are　crucial　for　certain　businesses.　However,　within　SAGIN　there　is　a　significant　variance　in　performance　among　different　types　of　radio　access　networks　(RANs).　This　necessitates　a　reconsideration　of　system　architecture　and　handover　selection　schemes　to　meet　the　quality　of　service　(QoS)　requirements　of　various　business　applications.　The　main　focus　of　this　article　is　to　explore　the　integration　of　sensing　and　mobile　edge　computing　(MEC)　with　SAGIN　and　also　to　examine　the　system　architecture,　selection　schemes,　and　handover　procedures.　We　first　provide　an　overview　of　SAGIN＇s　capabilities　and　highlight　its　integrated　architecture.　Subsequently,　we　introduce　several　handover　selection　schemes,　followed　by　an　elaboration　on　the　redesigned　handover　procedure　for　SAGIN.　Finally,　we　present　some　simulation　results　and　discuss　challenges　that　need　to　be　addressed　in　practical　implementation.