Global G-protein Coupled Receptor Market By Type (Calcium Level Detection Assays, GTPS Binding Assays, cGMP Assays, Reporter Gene Assays, Receptor Internalization Assays, and cAMP Assays), By Application (Cardiovascular System, Central Nervous System, Respiratory System, Immune System, Reproductive System, and Oncology), By Region, and Key Companies - Industry Segment Outlook, Market Assessment, Competition Scenario, Trends and Forecast 2019-2028