Primer binding site
A primer binding site is a region of a nucleotide sequence where an RNA or DNA single-stranded primer binds to start replication. The primer binding site is on one of the two complementary strands of a double-stranded nucleotide polymer, in the strand which is to be copied, or is within a single-stranded nucleotide polymer sequence.
A PCR primer binding site is a site where a polymerase chain reaction primer binds, to prime duplication of a complement to an existing DNA or RNA sequence.
The HIV primer binding site is a structured RNA element in the genomes of retroviruses to which tRNA binds to initiate reverse transcription. In HIV, the tRNA is tRNA although it can use other tRNAs. It consists of 18 nucleotides and follows the U5 region of the 5'-long terminal repeat of the retrovirus.