Catalyzes the attachment of alanine to tRNA(Ala) in a two- step reaction: alanine is first activated by ATP to form Ala-AMP and then transferred to the acceptor end of tRNA(Ala) (PubMed:27622773, PubMed:27911835, PubMed:28493438, PubMed:33909043). Also edits incorrectly charged tRNA(Ala) via its editing domain (PubMed:27622773, PubMed:27911835, PubMed:28493438, PubMed:29273753). In presence of high levels of lactate, also acts as a protein lactyltransferase that mediates lactylation of lysine residues in target proteins, such as TEAD1, TP53/p53 and YAP1 (PubMed:38512451, PubMed:38653238). Protein lactylation takes place in a two-step reaction: lactate is first activated by ATP to form lactate-AMP and then transferred to lysine residues of target proteins (PubMed:38512451, PubMed:38653238, PubMed:39322678). Acts as an inhibitor of TP53/p53 activity by catalyzing lactylation of TP53/p53 (PubMed:38653238). Acts as a positive regulator of the Hippo pathway by mediating lactylation of TEAD1 and YAP1 (PubMed:38512451). {ECO:0000269|PubMed:27622773, ECO:0000269|PubMed:27911835, ECO:0000269|PubMed:28493438, ECO:0000269|PubMed:29273753, ECO:0000269|PubMed:33909043, ECO:0000269|PubMed:38512451, ECO:0000269|PubMed:38653238, ECO:0000269|PubMed:39322678}. This is the function of ENSG00000090861 (AARS1, alanyl-tRNA synthetase 1).