Expression，co-localization and interaction analysis of mitochondrial membrane proteins prohibitin and stomatin-like protein 2 during spermatogenesis in Larimichthys polyactis.

To investigate the potential functions of mitochondrial membrane proteins prohibitin (PHB) and stomatin-like protein 2 (SLP2) during spermatogenesis in Larimichthys polyactis, we analyze the molecular characteristics and expression profiles of Lp-PHB and Lp-SLP2, the co-localization characteristics of Lp-PHB, Lp-SLP2 and mitochondria during spermatogenesis, as well as the co-localization characteristics of Lp-PHB, ubiquitin, and mitochondria. The results showed that Lp-PHB consists of an N-terminal hydrophobic, a conserved SPFH domain and a C-terminal helical domain, while Lp-SLP2 only contains a conserved SPFH domain. Lp-PHB and Lp-SLP2 genes and their encoded proteins were highly expressed in the testis, Lp-PHB and Lp-SLP2 protein were localized in the mitochondria of spermatogenic cells. During spermatogenesis, the signals of Lp-PHB and Lp-SLP2, Lp-PHB and mitochondria, as well as Lp-SLP2 and mitochondria were co-localized: in spermatogonia and spermatocytes, the co-localization signals were randomly distributed in the perinuclear cytoplasm; during the differentiation of spermatids into sperm, the co-localization signals gradually migrated to the tail region on one side of the nucleus; and in mature sperm, the co-localization signals accumulated in the middle piece. Additionally, the signals of Lp-PHB and ubiquitin, as well as ubiquitin and mitochondria, were also consistently co-localized during spermatogenesis, with co-localization characteristics highly similar to those of Lp-PHB and mitochondria. These results suggest that Lp-PHB and Lp-SLP2 may cooperate through interaction to maintain mitochondrial functional homeostasis during spermatogenesis in L. polyactis, and Lp-PHB may be involved in the degradation of damaged or excess mitochondria by mediating mitochondrial ubiquitination, thereby facilitating the normal progression of spermatogenesis.