Abstract:  Sensory neuron membrane proteins (SNMPs) are a class of membrane proteins uniquely to insects, typically possessing two characteristic transmembrane domains, and are also an important member of the CD36 family. Currently, insect SNMPs have been classified into five subfamily types, namely SNMP1, SNMP2, SNMP3, SNMP4 and SNMP5, each exhibiting distinct expression patterns across different insect species. SNMP1 subfamily genes, which are expressed in the antennae and olfactory sensory neurons (OSNs) of insects, have been extensively studied and confirmed to play a significant role in pheromone detection across various insect species. The widespread expression pattern of SNMP2 subfamily genes also suggests their role in olfaction and gustation. SNMP3 subfamily genes, which are specifically expressed in the midgut of lepidopteran insects, may function in digestion and immunity in insects. SNMP4 and SNMP5 subfamily genes which are unique to coleopteran insects, may be involved in a broader range of life activities in insects. Despite of the crucial role of SNMPs in insect olfactory system, the mechanism of action of SNMP1 with other receptor proteins has remained unclear. Additionally, research on the functions and mechanisms of action of the members of the other SNMP subfamilies especially in non-model insects remains limited. In this article, we summarized and discussed the diverse expression patterns of SNMP subfamily genes, various physiological and biological functions of SNMPs that may play in insect physiological activities, and the application of molecular biology, molecular genetics, heterologous cell expression systems, yeast two-hybrid, and other methods and technologies in the current functional study of insect SNMPs, providing references for future research on the function of insect SNMPs. Lastly, we put forward the following prospects of research focuses: (1) In-depth research on the relationship between SNMP1 and insect pheromones will contribute to the development of novel pheromone-based lures for pest control applications; (2) In the future, the use of artificial intelligence and protein structure analysis will aid in uncovering the mechanisms by which SNMPs interact with other receptor proteins to participate in odor recognition; and (3) Further research on other subfamilies of insect SNMPs in the realms of taste, digestion, immunity, and survival and development will not only enhance our understanding of the fundamental biological characteristics of insects but may also provide new strategies and methods for pest management.

Key words: Insects, sensory neuron membrane proteins, expression patterns, protein structure, odor recognition