Order 19-26,38-43,82-195,492-494,496-498,679-688,690-690,789-835,1407-1411,1416-1453,1459-1467,1469-1472,1487-1512,1535-1535,1537-1539,1541-1543,1545-1545,1567-1707
Histone methyltransferase that specifically methylates 'Lys-4' of histone H3, when part of the SET1 histone methyltransferase (HMT) complex, but not if the neighboring 'Lys-9' residue is already methylated. H3 'Lys-4' methylation represents a specific tag for epigenetic transcriptional activation. The non-overlapping localization with SETD1B suggests that SETD1A and SETD1B make non-redundant contributions to the epigenetic control of chromatin structure and gene expression (PubMed:12670868). May play a role in synaptic function and the development of neurons (PubMed:31197650).