Plays an important role in caveolae formation and organization. Essential for the formation of caveolae in all tissues (PubMed:18191225, PubMed:18840361, PubMed:18056712, PubMed:30188967). Core component of the CAVIN complex which is essential for recruitment of the complex to the caveolae in presence of calveolin-1 (CAV1) (PubMed:19546242). Essential for normal oligomerization of CAV1 (PubMed:23652019). Promotes ribosomal transcriptional activity in response to metabolic challenges in the adipocytes and plays an important role in the formation of the ribosomal transcriptional loop (PubMed:27528195). Dissociates transcription complexes paused by DNA-bound TTF1, thereby releasing both RNA polymerase I and pre-RNA from the template (PubMed:9582279, PubMed:11139612). The caveolae biogenesis pathway is required for the secretion of proteins such as GASK1A (PubMed:30188967). Component of the CAVIN complex composed of CAVIN1, CAVIN2, CAVIN3 and CAVIN4 (PubMed:19546242). Homotrimer (PubMed:25588833). Interacts with LIPE in the adipocyte cytoplasm (By similarity). Interacts with RNA polymerase I (PubMed:9582279). Interacts with TTF1 (PubMed:9582279, PubMed:27528195). Binds the 3' end of pre-rRNA (PubMed:9582279). Interacts with transcription factor ZNF148 (PubMed:10727401). Interacts with CAV1, CAVIN2 and CAVIN3 (PubMed:25588833, PubMed:19546242). Interacts with CAVIN4 (PubMed:19546242). Translocates to the cytoplasm from caveolae upon insulin stimulation (By similarity). Colocalizes with CAV1 in lipid rafts in adipocytes (PubMed:18056712). Localizes in the caveolae in a caveolin-dependent manner (PubMed:19546242). Expressed in the heart, stomach, adipose tissue and lung (at protein level). Expressed in testis, kidney, muscle, liver, spleen and brain. The leucine-zipper domain 1 is essential for its localization in the caveolae. Phosphorylated. Present in active and inactive forms. Changes in phosphorylation pattern may alter activity. Phosphorylation at Tyr-158 is essential for its function in the regulation of the ribosomal transcriptional activity. Monoubiquitinated. Mice show a metabolic phenotype of significantly reduced adipose tissue mass, higher circulating triglyceride levels, glucose intolerance, and hyperinsulinemia, consistent with a lipodystrophy. Cells from various tissues, including lung epithelium, intestinal smooth muscle, skeletal muscle, and endothelial cells showed no detectable caveolae cells. Belongs to the CAVIN family.