SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
X	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* Longitude Capital Partners II, LLC (Last) (First) (Middle) 2740 SAND HILL RD 2ND FLOOR (Street) MENLO PARK CA 94025 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol Aptinyx Inc. [ APTX ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 06/25/2018
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	06/25/2018		C		1,047,450(1)	A	(1)	1,047,450	I	By: Longitude Venture Partners II, L.P.(2)(3)
Common Stock	06/25/2018		C		1,197,076(1)	A	(1)	2,244,526	I	By: Longitude Venture Partners II, L.P.(2)(3)
Common Stock	06/25/2018		C		795,553(1)	A	(1)	3,040,079	I	By: Longitude Venture Partners II, L.P.(2)(3)
Common Stock	06/25/2018		P		150,000(4)	A	$16	3,190,079	I	By: Longitude Venture Partners II, L.P.(2)(3)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series A-1 Convertible Preferred Stock	(1)	06/25/2018		C			28,895,188	(1)	(1)	Common Stock	1,047,450	(1)	0	I	By: Longitude Venture Partners II, L.P.(2)(3)
Series A-2 Convertible Preferred Stock	(1)	06/25/2018		C			33,022,786	(1)	(1)	Common Stock	1,197,076	(1)	0	I	By: Longitude Venture Partners II, L.P.(2)(3)
Series B Convertible Preferred Stock	(1)	06/25/2018		C			21,946,301	(1)	(1)	Common Stock	795,553	(1)	0	I	By: Longitude Venture Partners II, L.P.(2)(3)

1. Name and Address of Reporting Person* Longitude Capital Partners II, LLC (Last) (First) (Middle) 2740 SAND HILL RD 2ND FLOOR (Street) MENLO PARK CA 94025 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Tammenoms Bakker Juliet (Last) (First) (Middle) 2740 SAND HILL RD 2ND FLOOR (Street) MENLO PARK CA 94025 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Longitude Venture Partners II, L.P. (Last) (First) (Middle) 2740 SAND HILL RD 2ND FLOOR (Street) MENLO PARK CA 94025 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. Each share of Series A-1 Convertible Preferred Stock, Series A-2 Convertible Preferred Stock and Series B Convertible Preferred Stock automatically converted into shares of Common Stock on a 27.58621-for-one basis immediately prior to the closing of the Issuer's initial public offering without payment or consideration. The shares of Series A-1 Convertible Preferred Stock, Series A-2 Convertible Preferred Stock and Series B Convertible Preferred Stock had no expiration date.

2. This statement is filed jointly by Longitude Capital Partners II, LLC ("Longitude Capital II"), Longitude Venture Partners II, L.P. ("Longitude Venture II"), and Juliet Tammenoms Bakker ("Ms. Bakker"), all of whom shared beneficial ownership of more than 10% of the capital stock of the Issuer as of the date of the transactions reported in this statement (but all of whom have ceased to share beneficial ownership of more than 10% of the capital stock of the Issuer as of the date of the filing of this statement and, as a result, are no longer subject to Section 16 of the Securities Exchange Act of 1934, as amended). The shares reported in this statement are held directly by Longitude Venture II. Longitude Capital II is the general partner of Longitude Venture II and may be deemed to share voting and investment power over the shares of the Issuer held by Longitude Venture II.

3. Ms. Bakker is a managing member of Longitude Capital II and may be deemed to share voting and investment power over the shares of the Issuer held by Longitude Venture II. Each of Longitude Capital II and Ms. Bakker disclaims beneficial ownership of such shares except to the extent of its or her pecuniary interest therein.

4. On June 25, 2018, Longitude Venture II purchased 150,000 shares of Common Stock of the Issuer at a price of $16.00 per share in the Issuer's initial public offering.

	LONGITUDE CAPITAL PARTNERS II, LLC, a Delaware limited liability company, By: /s/ Patrick G. Enright, Managing Member	06/26/2018
	LONGITUDE VENTURE PARTNERS II, L.P., By: Longitude Capital Partners II, LLC, a Delaware limited liability company, Its General Partner, By: /s/ Patrick G. Enright, Managing Member	06/26/2018
	/s/ Juliet Tammenoms Bakker	06/26/2018
	** Signature of Reporting Person	Date
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