$VAR1 = undef;

Summary for peptidase A01.001: pepsin A

Names
MEROPS Name	pepsin A
Other names	pepsin isoenzyme 3b, pepsin A3, pepsinogen A, pepsinogen A3, PGA3 g.p. (Homo sapiens)

Domain architecture

MEROPS Classification
Classification	Clan AA >> Subclan (none) >> Family A1 >> Subfamily A >> A01.001
Holotype	pepsin A (Homo sapiens), Uniprot accession P0DJD8 (peptidase unit: 63-388), MERNUM MER0000885
History	Identifier created: Handbook of Proteolytic Enzymes (1998) Academic Press, London.

Activity
Catalytic type	Aspartic
Peplist	Included in the Peplist with identifier PL00001
NC-IUBMB	Subclass 3.4 (Peptidases) >> Sub-subclass 3.4.23 (Aspartic endopeptidases) >> Peptidase 3.4.23.1
Enzymology	BRENDA database
Proteolytic events	CutDB database (2 cleavages)
Physiology	Contributes to proteolysis in the vertebrate stomach.
Pharmaceutical relevance	Elevated blood levels of pepsinogen 1 have been reported to correlate with predisposition to gastric ulcer, but both may result from infection with Helicobacter pylori (Mertz et al., 2000). The effectiveness of pepstatin in preventing the pathogenesis of reflux esophagitis in a rat model led to the conclusion that pepsin plays a major pathogenic role in the development of acid reflux esophagitis (Nagahama et al., 2006). However, it is not clear to MEROPS that rodents express a form of pepsin that is truly comparable to the human one.
Pathways	KEGG	Protein digestion and absorption
Other databases	WIKIPEDIA	http://en.wikipedia.org/wiki/Pepsin
Cleavage site specificity	Explanations of how to interpret the following cleavage site sequence logo and specificity matrix can be found here.
Cleavage pattern	-/-/-/--/-/-/- (based on 970 cleavages)

Specificity matrix

Amino acid	P4	P3	P2	P1	P1'	P2'	P3'	P4'
Gly	56	78	58	39	25	38	40	57
Pro	93	51	9	7	29	16	21	45
Ala	58	92	63	74	73	93	57	59
Val	60	72	68	38	84	98	60	51
Leu	64	109	84	187	129	76	144	86
Ile	47	69	65	23	79	53	63	45
Met	24	34	30	53	38	16	20	27
Phe	39	26	32	141	70	25	39	33
Tyr	41	25	26	46	60	30	38	22
Trp	9	8	9	14	12	4	8	8
Ser	41	74	66	25	39	65	64	53
Thr	65	75	65	53	52	66	45	57
Cys	10	12	21	16	11	14	14	12
Asn	40	30	48	29	35	37	32	43
Gln	38	31	46	30	21	33	46	40
Asp	59	50	57	50	49	47	56	47
Glu	78	75	105	104	53	74	63	75
Lys	74	32	58	21	56	81	87	82
Arg	36	10	40	15	35	84	40	49
His	23	6	12	3	15	13	20	26

Human genetics
Gene symbol	Locus	Megabases	Ensembl	Entrez gene	Gene Cards	OMIM
PGA3	11q13		ENSG00000180860	5220	PGA3	169710