Loop: The default is a 10-nucleotide spacer (TTGATATCCG), and other spacers have been reported as well: CCACC , CTCGAG , AAGCTT , CCACACC , TTCAAGAGA.

Transcription Start Site: RNA Polymerase III prefers to initiate transcription with a purine . If the hairpin insert does not start with a "G" or "A", an additional "G" will be added to the 5' end of the hairpin insert sequence.

Vector: Vector specific sequences will be added based on vendor recommendation. Those sequences could include:
5' Sequence
3' Sequence
Loop Sequence
Transcription Start Site

Dinucleotide Leader Sequence: Please do not include the dinucleotide leader sequence "AA" in the sense target sequence. The "AA" leader is not required for vector-based siRNA contruct.

Orientation of hairpin insert:. Hairpin insert can be constructed in these orientations: antisense-loop-sense (Default), or sense-loop-antisense (Reverse). Both orientations can function effectively.

Use this tool to build small hairpin inserts for use as siRNA expression vectors.


1, Paste each sense siRNA sequence (please do not include the dinucleotide leader sequence "AA") or use our batch build form to paste all the sequences at once.
2, You can specify the loop sequence (or use the default sequence) for each target (sense siRNA).
3, You need to pick your desired vector if you want to create the inserts for vector-based siRNA.
4, You can select the number and click the following button: to build more targets at once.


Do you like the current new website?