The function of ENSG00000149577 (SIDT2, SID1 transmembrane family member 2) is as follows. Mediates the translocation of RNA and DNA across the lysosomal membrane during RNA and DNA autophagy (RDA), a process in which RNA or DNA is directly imported into lysosomes in an ATP- dependent manner, and degraded (PubMed:27046251, PubMed:27846365). Involved in the uptake of single-stranded oligonucleotides by living cells, a process called gymnosis (PubMed:28277980). In vitro, mediates the uptake of linear DNA more efficiently than that of circular DNA, but exhibits similar uptake efficacy toward RNA and DNA. Binds long double-stranded RNA (dsRNA) (500 - 700 base pairs), but not dsRNA shorter than 100 bp (By similarity). {ECO:0000250|UniProtKB:Q8CIF6, ECO:0000269|PubMed:27046251, ECO:0000269|PubMed:27846365, ECO:0000269|PubMed:28277980}.