sl5 is a deletion of the sequence TGATAGCCGCACGTC, this results in the deletion of the amino acids LIAAR, aa#1115-1119. The remaining C in the codon for aa#1115 is fused to the remaining AT of codon #1120, thus retaining the His encoded by codon #1120.
The sequence "TGATAGCCGCACGTC" is deleted, resulting in the deletion of amino acids 1115-1119 (LIAAR) from the expressed product. The remaining C amino acid residue from before the deleted sequence is fused to the AT of codon 1120, meaning that the mutated protein retains the His encoded by codon 1120.
In-fame deletion of 15bp that removes 5 amino acids from the C2 domain.